OFFSET
1,1
COMMENTS
Subsequence of A035092. - Amiram Eldar, Mar 01 2019
EXAMPLE
2*((2^2-1)^2)+1=19 prime so a(1)=2.
MATHEMATICA
a[n_] := Module[{k = 1, m = (2^MersennePrimeExponent[n] - 1)^2}, While[! PrimeQ[k*m + 1], k++]; k]; Array[a, 20] (* Amiram Eldar, Mar 01 2019 *)
CROSSREFS
KEYWORD
more,nonn
AUTHOR
Pierre CAMI, Oct 08 2004
EXTENSIONS
a(19)-a(22) from Donovan Johnson, Mar 23 2008
a(23)-a(26) from Amiram Eldar, Mar 01 2019
STATUS
approved