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A201364 Numbers n such that A057775(n) is the factor of a Fermat number 2^(2^m) + 1 for some m. 5
1, 2, 4, 7, 8, 14, 16, 25, 39, 41, 57, 67, 75, 120, 127, 147, 209, 229, 231, 290, 302, 320, 455, 547, 558, 747, 1553, 1947, 2027, 2458, 3313, 3508, 4262, 4727, 6210, 6393, 6539, 6838, 7312, 8242, 8557, 9431, 9450 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

COMMENTS

Indices of Fermat factors in A057775.

No other terms below 10^4.

LINKS

Table of n, a(n) for n=1..43.

Wilfrid Keller, Fermat factoring status

Eric Weisstein's World of Mathematics, Fermat Number

MATHEMATICA

lst = {}; Do[k = 1; While[! PrimeQ[p = (2*k - 1)*2^n + 1], k++]; If[IntegerQ[Log[2, MultiplicativeOrder[2, p]]], AppendTo[lst, n]], {n, 320}]; lst

CROSSREFS

Cf. A000215, A057775, A057778.

Sequence in context: A062846 A102824 A324588 * A225318 A308267 A177805

Adjacent sequences:  A201361 A201362 A201363 * A201365 A201366 A201367

KEYWORD

nonn

AUTHOR

Arkadiusz Wesolowski, Nov 30 2011

STATUS

approved

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Last modified October 20 20:24 EDT 2019. Contains 328273 sequences. (Running on oeis4.)