|
%I #10 Mar 30 2012 17:39:12
%S 4,11,137,32897,2147516417,9223372039002259457,
%T 170141183460469231740910675752738881537,
%U 57896044618658097711785492504343953926805133516280751251460479307672448925697
%N a(n) = 2^(2^n - 1) + 2^(2^(n + 1) - 1) + 1.
%C Fermat-like sequence of powers of two.
%C Average of two consecutive Fermat numbers. - Juri-Stepan Gerasimov, Aug 26 2011.
%F a(n) = A058891(n+1)+A058891(n+2)+1. - _R. J. Mathar_, Apr 22 2007
%F a(n) = (A000215(n)+A000215(n+1))/2. - Juri-Stepan Gerasimov, Aug 26 2011.
%t aa = Table[2^(2^n - 1) + 2^(2^(n + 1) - 1) + 1, {n, 0, 10}]
%K nonn
%O 0,1
%A _Roger L. Bagula_, May 31 2006
%E Edited by _N. J. A. Sloane_, Jun 03 2006
| 