A057595 - OEIS

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A057595

Triangle T(n,k) giving 2*p mod n-1, where p = period of sequence k^i (i=0,1,2,...) mod n (n >= 2, 2<=k<=n).

0, 0, 0, 2, 1, 2, 0, 0, 0, 2, 4, 2, 2, 4, 2, 0, 0, 0, 0, 4, 2, 2, 4, 2, 4, 2, 4, 2, 4, 2, 6, 4, 2, 6, 4, 2, 8, 8, 4, 2, 2, 8, 8, 4, 2, 0, 0, 0, 0, 0, 0, 0, 0, 4, 2, 4, 4, 2, 4, 2, 4, 4, 2, 2, 4, 2, 0, 6, 0, 8, 0, 0, 8, 6, 0, 0, 4, 2

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

OFFSET

2,4

LINKS

Table of n, a(n) for n=2..79.

EXAMPLE

0; 0,0; 2,1,2; 0,0,0,2; ...

MATHEMATICA

period[lst_] := Module[{n, i, j}, n = Length[lst]; For[j = 2, j <= n, j++, For[i = 1, i < j, i++, If[lst[[i]] == lst[[j]], Return[{i - 1, j - i}]]]]; Return[{0, 0}]]; T[n_, k_] := Module[{t, p}, t = Table[PowerMod[k, i, n], {i, 0, 2 n}]; p = period[t][[2]]; Mod[2 p, n - 1]]; Table[T[n, k], {n, 2, 13}, {k, 2, n}] // Flatten (* Jean-François Alcover, Feb 04 2015 *)

CROSSREFS

Cf. A057593, A057594.

Sequence in context: A050602 A065040 A284688 * A035201 A035179 A035161

Adjacent sequences: A057592 A057593 A057594 * A057596 A057597 A057598

KEYWORD

nonn,tabl,nice

AUTHOR

Gottfried Helms, Oct 05 2000

STATUS

approved