%I #2 Mar 30 2012 17:33:56
%S 1,4,64,1024,4194304,1073741824,17179869184,288230376151711744
%N 2^(2p-1)/8, where p is A000043(n).
%C Ultraperfect numbers (A139306), divided by 8.
%F a(n) = A139306(n)/8 = A152921(n)/4 = A152922(n)/2.
%Y Cf. A000043, A139292, A139306, A152921, A152922.
%K nonn
%O 1,2
%A _Omar E. Pol_, Dec 15 2008
|