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A188465 Primes p such that p^2 divides 2^(2^(p-1)-1) - 1. 1
7, 73, 127, 337, 487, 601, 881, 937, 1801, 2593, 2647, 3079, 3943, 4057, 4201, 6553, 7993, 9199, 10657, 14407, 15289, 16759, 18041, 18121, 20521, 20809, 21673, 22111, 24967, 25111, 26407, 28393, 28729, 36793, 39367, 41161, 42463, 47737, 47881, 49201, 49297 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

LINKS

Arkadiusz Wesolowski, Table of n, a(n) for n = 1..200

MAPLE

isA188465 := proc(p) local m; if isprime(p) then m := modp(2 &^ ( (2 ^ (p-1))-1)-1, p) ; m := simplify(m) ; if m = 0 then true; else false; end if; else false; end if; end proc:

for i from 1 do p := ithprime(i) ; if isA188465(p) then printf("%d\n", p) ; end if; end do: # R. J. Mathar, Apr 10 2011

MATHEMATICA

okQ[p_] := Module[{k = MultiplicativeOrder[2, p^2]}, PowerMod[2, p - 1, k] == 1]; Select[Prime[Range[5000]], okQ] (* T. D. Noe, Apr 11 2011 *)

CROSSREFS

Cf. A001220.

Sequence in context: A321077 A080794 A082719 * A142053 A012049 A012158

Adjacent sequences:  A188462 A188463 A188464 * A188466 A188467 A188468

KEYWORD

nonn

AUTHOR

Arkadiusz Wesolowski, Apr 10 2011

STATUS

approved

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Last modified November 18 01:41 EST 2019. Contains 329242 sequences. (Running on oeis4.)