%I
%S 3,7,17,198,71,88,29,50,9,225,26,141,10,79,36,89,281,108,43,233,156,
%T 412,430,296,79,20,76,178,80,54,1018,82,89,403,85,208,914,373,1226,62,
%U 192,68,390,1055,1500,137,1018,141,95,54,160,52,11,754,674,182,517
%N a(n) is the smallest positive integer k such that k^128 + 1 == 0 mod p, where p is the nth prime of the form 1 + 256*b (see A208178).
%C A208178(n): primes of form 256n+1.
%e a(1) = 3 because 3^128+1 = 2
%e * 257 * 275201 * 138424618868737 * 3913786281514524929 * 153849834
%e 853910661121 with A208178(1) = 257.
%t aa = {}; Do[p = Prime[n]; If[Mod[p, 256] == 1, k = 1; While[ ! Mod[k^128 + 1, p] == 0, k++ ]; AppendTo[aa, k]], {n, 5000}]; aa
%Y Cf. A208178.
%K nonn
%O 1,1
%A _Michel Lagneau_, Oct 22 2012
