1,2

Table of n, a(n) for n=1..6.

5 is in the sequence, since prime(5)=11 and (2*11-1)^(2*11-1) mod 2^(2*11-1) = 21^21 mod 2^21 = 1472837 is prime.

Cf. A000040, A000079, A000312, A178537, A178966.

Sequence in context: A134077 A120128 A019149 * A244274 A279664 A230461

Adjacent sequences: A172994 A172995 A172996 * A172998 A172999 A173000

nonn

Juri-Stepan Gerasimov, Jan 01 2011

approved