A219341 Least prime k such that k*2^n + 1 divides 2^k - 1, or 0 if no such prime exists.

2, 3, 0, 11, 397, 839, 1459, 2081, 7297, 53849, 3499, 70589, 792277, 20399, 11173873, 929057, 232591, 6782759, 5834299, 26812151, 40269673, 88529891, 368454343, 616767917, 1167319801, 709939943, 38151887029, 38617336361, 23280518791, 168046587719, 882701485339

Offset

0,1

Comments

If a(n) > 0, then a(n)*2^n + 1 is in A122094.

Links

Table of n, a(n) for n=0..30.

G. L. Honaker, Jr. and Chris Caldwell, Prime Curios! 232591

Eric Weisstein's World of Mathematics, Mersenne Number

Mathematica

lst = {}; Do[k = 2; If[n == 2, AppendTo[lst, 0], While[True, If[PrimeQ[k], f = k*2^n + 1; If[PrimeQ[f] && PowerMod[2, k, f] == 1, AppendTo[lst, k]; Break[]]]; k++]], {n, 0, 13}]; lst

Crossrefs

Cf. A001348, A002144.

Sequence in context: A012404 A002099 A265514 * A059740 A005160 A085042

Adjacent sequences: A219338 A219339 A219340 * A219342 A219343 A219344

Keyword

nonn,changed

Author

Arkadiusz Wesolowski, Nov 18 2012

Extensions

a(26)-a(30) from Jason Yuen, May 24 2024

Status

approved