A278248 - OEIS

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A278248

Least number with the same prime signature as the n-th number in Perrin sequence: a(n) = A046523(A001608(n)), a(1) = 0.

2, 0, 2, 2, 2, 2, 2, 2, 6, 12, 2, 6, 2, 6, 6, 12, 60, 6, 6, 6, 2, 2, 96, 60, 2, 30, 6, 6, 6, 840, 30, 6, 30, 6, 2, 6, 6, 60, 2, 420, 1260, 30, 30, 420, 210, 30, 30, 210, 6, 30, 30, 12, 6, 2310, 30, 840, 6, 240, 6, 30, 6, 420, 6, 6, 30, 420, 6, 210, 6, 6, 6, 4620, 60, 210, 30030, 2, 6, 30, 2310, 13860, 60, 210, 6, 6, 6, 120, 6, 2310, 210, 210, 6, 210, 30, 60, 4620

(list; graph; refs; listen; history; text; internal format)

OFFSET

0,1

COMMENTS

This sequence works as a "sentinel" for Perrin sequence by matching to any other sequence that is obtained as f(A001608(n)), where f(n) is any function that depends only on the prime signature of n (see the index entry for "sequences computed from exponents in ..."). As of Nov 11 2016 no such sequences were present in the database.

LINKS

Antti Karttunen, Table of n, a(n) for n = 0..555

Index entries for sequences computed from exponents in factorization of n

FORMULA

a(1) = 0; for any other n, a(n) = A046523(A001608(n)).

PROG

(PARI)

A046523(n) = my(f=vecsort(factor(n)[, 2], , 4), p); prod(i=1, #f, (p=nextprime(p+1))^f[i]) \\ From Charles R Greathouse IV, Aug 17 2011

p0 = 3; p1 = 0; p2 = 2; for(n=0, 555, write("b278248.txt", n, " ", if(!p0, p0, A046523(p0))); old_p0 = p0; old_p1 = p1; p0 = p1; p1 = p2; p2 = old_p1 + old_p0; );

(Scheme) (define (A278248 n) (if (= 1 n) 0 (A046523 (A001608 n))))

CROSSREFS

Cf. A001608, A046523, A278241, A278245.

Sequence in context: A044949 A044950 A161872 * A036461 A244478 A261153

Adjacent sequences: A278245 A278246 A278247 * A278249 A278250 A278251

KEYWORD

nonn

AUTHOR

Antti Karttunen, Nov 16 2016

STATUS

approved