A218164 a(n) is the smallest positive integer k such that k^64 + 1 == 0 mod p, where p is the n-th prime of the form 1 + 128*b (see A208177).

9, 21, 5, 38, 21, 31, 33, 63, 42, 66, 118, 131, 202, 29, 28, 31, 58, 171, 94, 182, 309, 182, 81, 272, 110, 175, 657, 491, 42, 100, 523, 244, 168, 199, 145, 138, 79, 73, 357, 826, 210, 541, 523, 215, 98, 220, 1478, 22, 92, 178, 50, 709, 250, 2523, 630, 218, 7

Offset

1,1

Comments

A208177 : primes of the form 128*k+1.

Links

Table of n, a(n) for n=1..57.

Example

a(1) = 9 because 9^64+1 = 2 * 257 * 275201 * 138424618868737 * 3913786281514524929 * 153849834853910661121 with A208177(1) = 257.

Mathematica

spi[n_]:=Module[{k=1}, While[PowerMod[k, 64, n]!=n-1, k++]; k]; spi/@Select[128 Range[500]+1, PrimeQ] (* Harvey P. Dale, Jan 19 2021 *)

Crossrefs

Cf. A208177.

Sequence in context: A008847 A143243 A157812 * A161326 A250783 A259250

Adjacent sequences: A218161 A218162 A218163 * A218165 A218166 A218167

Keyword

nonn

Author

Michel Lagneau, Oct 22 2012

Extensions

Corrected by Harvey P. Dale, Jan 19 2021

Status

approved