OFFSET
1,1
COMMENTS
Conjecture: primorial numbers (A002110) are terms of this sequence.
MATHEMATICA
Table[SelectFirst[Range[10^5], PowerMod[2^#, 2 n, 4 n^2 - 1] == 1 &] /. k_ /; k != n - 1 -> Nothing, {n, 620}] + 1 (* Version 10.2, or *)
Rest@ Union@ Table[If[# == n - 1, #, 0] &@ Block[{m = 1}, While[PowerMod[2^m, 2 n, 4 n^2 - 1] != 1, m++]; m], {n, 620}] + 1 (* Michael De Vlieger, May 06 2016, after Giovanni Resta at A281363 *)
CROSSREFS
KEYWORD
nonn,easy
AUTHOR
Juri-Stepan Gerasimov, May 06 2016
STATUS
approved