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Index of first occurrence of n in A278567.
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1
1, 7, 42, 385, 436, 1530, 3180, 3625, 8208, 3767, 10116, 6699
Irregular triangle read by rows: coefficients of cyclotomic polynomial Phi_n(x) (exponents in increasing order).
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35
0, 1, -1, 1, 1, 1, 1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 1, -1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, 0, 0, 1, 1, 0, 0, 1, 0, 0, 1, 1, -1, 1, -1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 0, -1, 0, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, -1, 1, -1, 1, -1, 1, 1, -1, 0, 1, -1, 1, 0, -1, 1
COMMENTS
We follow Maple in defining Phi_0 to be x; it could equally well be taken to be 1.
The length of row n >= 1 of this table is phi(n) + 1 = A000010(n) + 1. Row n = 0 has here length 2. Phi_n(x) is the minimal polynomial of omega_n := exp(i*2*Pi/n) over the rationals. Namely, Phi_n(x) = Product_{k=0..n-1, gcd(k,n)=1} (x - (omega_n)^k). See the Graham et al. reference, 4.50 a, pp. 149, 506.
Phi_n(x) = Product_{d|n} (x^d - 1)^(mu(n/d)) with the Moebius function mu(n) = A008683(n), n >= 1. See the Graham et al. reference, 4.50 b, pp. 149, 506. Phi_n(x) = Phi_{rad(n)}(x^(n/rad(n))), n >= 2, with rad(n) = A007947(n), the squarefree kernel of n. Proof from the preceding formula, where only squarefree n/d ( A005117) from the set of divisors of n enter, by mapping each factor (numerator or denominator) of the left hand side to one of the right hand side and vice versa. (End)
Each row can be considered as the last column of the companion matrix of the cyclotomic polynomial: A000010(n) is the size of such a square matrix, last column has opposite signs and the last term (before last term of each row in A013595) equal to A008683(n). - Eric Desbiaux, Dec 14 2015
REFERENCES
E. R. Berlekamp, Algebraic Coding Theory, McGraw-Hill, 1968; see p. 90.
Z. I. Borevich and I. R. Shafarevich, Number Theory. Academic Press, NY, 1966, p. 325.
R. L. Graham, D. E. Knuth and O. Patashnik, Concrete Mathematics, Addison-Wesley, 1991, p. 137.
K. Ireland and M. Rosen, A Classical Introduction to Modern Number Theory, Springer, 1982, p. 194.
EXAMPLE
Phi_0 = x; Phi_1 = x - 1; Phi_2 = x + 1; Phi_3 = x^2 + x + 1; Phi_4 = x^2 + 1; ...
The irregular triangle a(n,m) begins:
n\m 0 1 2 3 4 5 6 7 8 9 10 11 12 ...
0: 0 1
1: -1 1
2: 1 1
3: 1 1 1
4: 1 0 1
5: 1 1 1 1 1
6: 1 -1 1
7: 1 1 1 1 1 1 1
8: 1 0 0 0 1
9: 1 0 0 1 0 0 1
10: 1 -1 1 -1 1
11: 1 1 1 1 1 1 1 1 1 1 1
12: 1 0 -1 0 1
13: 1 1 1 1 1 1 1 1 1 1 1 1 1
14: 1 -1 1 -1 1 -1 1
15: 1 -1 0 1 -1 1 0 -1 1
...
Phi_15(x) = (x^1 - 1)*((x^3 - 1)^(-1))*((x^5 - 1)^(-1))*(x^15 - 1) because mu(15) = mu(1) = +1 and mu(3) = mu(5) = -1. Hence Phi_15(x) = 1 - x + x^3 - x^4 + x^5 - x^7 + x^8, giving row n = 15.
Example for the reduction via the squarefree kernel: Phi_12(x) = Phi_6(x^(12/6)) = Phi_6(x^2). By the formula with the Mobius function Phi_6(x) = Phi_2(x^3)/Phi_2(x) = 1 - x + x^2 and with x -> x^2 this becomes Phi_12(x) = 1 - x^2 + x^4.
(End)
MAPLE
N:= 100: # to get coefficients up to cyclotomic(N, x)
with(numtheory):
for n from 0 to N do
C:= cyclotomic(n, x);
L[n]:= seq(coeff(C, x, i), i=0..degree(C));
od:
A:= [seq](L[n], n=0..N): # note that A013595(n) = A[n+1]
MATHEMATICA
Table[CoefficientList[x^KroneckerDelta[n] Cyclotomic[n, x], x], {n, 0, 15}] // Flatten (* Peter Luschny, Dec 27 2016 *)
PROG
(PARI) row(n) = if (n==0, p=x, p = polcyclo(n)); Vecrev(p); \\ Michel Marcus, Dec 14 2015
Indices of records in heights of cyclotomic polynomials ( A160338).
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9
1, 105, 385, 1365, 1785, 2805, 3135, 6545, 10465, 11305, 17255, 20615, 26565, 40755, 106743, 171717, 255255, 279565, 327845, 707455, 886445, 983535, 1181895, 1752465, 3949491, 8070699, 10163195, 13441645, 15069565, 30489585, 37495115, 40324935
MATHEMATICA
r = 0; Do[If[# > r, r = #; Print[n]] &@ Max@ Abs@ CoefficientList[Cyclotomic[n, x], x], {n, 10^4}] (* Michael De Vlieger, May 20 2024 *)
PROG
(PARI) print1(r=1); for(n=2, 1e4, t=vecmax(abs(Vec(polcyclo(n)))); if(t>r, r=t; print1(", "n))) \\ Charles R Greathouse IV, Jun 28 2012
Least k such that the k-th cyclotomic polynomial has n as a coefficient.
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6
4, 1, 165, 595, 1785, 1785, 2805, 3135, 6545, 6545, 10465, 10465, 10465, 10465, 10465, 11305, 11305, 11305, 11305, 11305, 11305, 11305, 15015, 11305, 20615, 17255, 20615, 20615, 26565, 26565, 26565, 26565, 26565, 26565, 26565, 26565, 26565, 26565, 26565, 26565, 26565
COMMENTS
Suzuki proves that a(n) exists for each n. Vaughan proves that there are infinitely many k with a(n) = k and n > exp(exp(log 2 * log k/log log k)).
EXAMPLE
Phi(165) = x^80 + x^79 + x^78 - x^75 - x^74 - x^73 - x^69 - x^68 - x^67 + x^65 + 2x^64 + 2x^63 + x^62 - x^60 - x^59 - x^58 - x^54 - x^53 - x^52 + x^50 + 2x^49 + 2x^48 + 2x^47 + x^46 - x^44 - x^43 - x^42 - x^41 - x^40 - x^39 - x^38 - x^37 - x^36 + x^34 + 2x^33 + 2x^32 + 2x^31 + x^30 - x^28 - x^27 - x^26 - x^22 - x^21 - x^20 + x^18 + 2x^17 + 2x^16 + x^15 - x^13 - x^12 - x^11 - x^7 - x^6 - x^5 + x^2 + x + 1, with 2 as the coefficient of x^16 (among others), and this is the least k for which 2 appears, so a(2) = 165.
MAPLE
N:= 40: count:= 0: A:= Array(0..N): A[0]:= 4:
for k from 1 while count < N do
S:= select(t -> t::posint and t <= N and A[t] = 0, {coeffs(numtheory:-cyclotomic(k, x), x)}):
if S <> {} then
A[convert(S, list)]:= k;
count:= count + nops(S);
fi
od:
MATHEMATICA
Table[k = 1; While[! MemberQ[CoefficientList[Cyclotomic[k, x], x], n], k++]; k, {n, 0, 9}] (* Michael De Vlieger, Sep 29 2015 *)
PROG
(PARI) a(n)=my(k, v); while(!setsearch(Set(Vec(polcyclo(k++))), n), ); k
Least k such that the k-th cyclotomic polynomial has -n as a coefficient.
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5
4, 1, 105, 385, 1365, 2145, 2805, 3135, 6545, 7917, 10465, 10465, 10465, 10465, 10465, 11305, 11305, 11305, 11305, 11305, 11305, 11305, 15015, 17255, 17255, 17255, 20615, 25935, 26565, 26565, 26565, 26565, 26565, 26565, 26565, 26565, 26565, 26565, 26565, 26565, 26565, 26565
COMMENTS
Suzuki proves that a(n) exists for each n.
EXAMPLE
Phi(105) = x^48 + x^47 + x^46 - x^43 - x^42 - 2x^41 - x^40 - x^39 + x^36 + x^35 + x^34 + x^33 + x^32 + x^31 - x^28 - x^26 - x^24 - x^22 - x^20 + x^17 + x^16 + x^15 + x^14 + x^13 + x^12 - x^9 - x^8 - 2x^7 - x^6 - x^5 + x^2 + x + 1, with -2 as the coefficient of x^7 (among others), and this is the least k for which -2 appears, so a(2) = 105.
MATHEMATICA
Table[k = 1; While[! MemberQ[CoefficientList[Cyclotomic[k, x], x], -n], k++]; k, {n, 0, 9}] (* Michael De Vlieger, Sep 29 2015 *)
PROG
(PARI) a(n)=my(k, v); while(!setsearch(Set(Vec(polcyclo(k++))), -n), ); k
a(n) = maximum absolute value of coefficients in the cyclotomic polynomial C(N,x), where N = n-th number which a product of three distinct odd primes = A046389(n).
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2
2, 2, 2, 1, 2, 2, 2, 2, 2, 3, 1, 2, 1, 2, 1, 1, 2, 2, 3, 2, 2, 2, 2, 1, 1, 3, 2, 2, 1, 2, 2, 2, 2, 1, 1, 2, 1, 1, 3, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 2, 1, 2, 1, 2, 1, 2, 3, 2, 2, 2, 1, 2, 3, 1, 1, 1, 2, 2, 2, 1, 2, 3, 1, 2, 3, 2, 2, 1, 2, 2, 2, 1, 2, 1, 2, 2, 2, 2, 1, 2, 2, 2, 2, 3, 1, 2, 2, 2, 1, 3, 2
REFERENCES
Don Reble, Posting to Sequence Fans Mailing List, Nov 26 2016
MAPLE
with(numtheory):
b:= proc(n) option remember; local k;
for k from 2+`if`(n=1, 1, b(n-1)) by 2 while
bigomega(k)<>3 or nops(factorset(k))<>3 do od; k
end:
a:= n-> max(map(abs, [coeffs(cyclotomic(b(n), x))])):
MATHEMATICA
b[n_] := b[n] = (For[k = 2 + If[n == 1, 1, b[n-1]], PrimeOmega[k] != 3 || PrimeNu[k] != 3, k += 2]; k);
a[n_] := Max @ Abs @ CoefficientList[Cyclotomic[b[n], x], x];
Maximal coefficient (in absolute value) in the numerator of C({1..n},x).
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1
1, 1, 2, 17, 444, 66559954, 14648786369948422, 791540878703169050660325841979096789557779, 1918013047695258943191946313451491492494186620117241479813740479213857275772347178176158
FORMULA
C({s},x) = Sum_{i in {s}} (C({s}-{i},x)*x^i)/(1 - Sum_{i in {s}} (x^i)) with C({},x) = 1.
EXAMPLE
C_x({1,2,3},x) = (-x^15 - 5*x^14 - 12*x^13 - 17*x^12 - 11*x^11 + 4*x^10 + 16*x^9 + 10*x^8 - 6*x^6)/(x^15 + 4*x^14 + 7*x^13 + 4*x^12 - 8*x^11 - 18*x^10 - 13*x^9 + 7*x^8 + 19*x^7 + 11*x^6 - 6*x^5 - 10*x^4 - 2*x^3 + 3*x^2 + 2*x - 1) with maximal coefficient abs(-17) in the numerator, so a(3) = 17.
PROG
(PARI)
C_x(s)={my(g=if(#s <1, 1, sum(i=1, #s, C_x(s[^i])*x^(s[i]))/(1-sum(i=1, #s, x^(s[i]))))); return(g)}
a(n)={vecmax(abs(Vec(numerator(C_x([1..n])))))}
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