A226018 Numbers n such that prime(n) divides 2^(n-1) + 1.

1, 2, 3, 25, 183, 6463, 599806, 10553830, 15377521, 211655508, 603977457, 609080388, 3637001051, 8073907744

Offset

1,2

Comments

a(15) > 10^10. - Giovanni Resta, May 23 2013

Links

Table of n, a(n) for n=1..14.

Example

The 25th prime is 97, and 97 divides 2^(25-1) + 1 = 16777217, so 25 is in the sequence.

Mathematica

Select[Range[10^6], (p = Prime[#]; PowerMod[2, # - 1, p] == p - 1) &] (* Giovanni Resta, May 23 2013 *)

Crossrefs

Sequence in context: A295328 A281169 A296281 * A094998 A208203 A109586

Adjacent sequences: A226015 A226016 A226017 * A226019 A226020 A226021

Keyword

nonn

Author

Gerasimov Sergey, May 23 2013

Extensions

a(5)-a(14) from Giovanni Resta, May 23 2013

Status

approved