%I #5 Mar 14 2020 05:55:37
%S 0,1,7,31,2047,32767,131071,536870911,576460752303423487,
%T 154742504910672534362390527,40564819207303340847894502572031,
%U 42535295865117307932921825928971026431
%N Even superperfect numbers divided by 2, minus 1.
%F a(n) = (A061652(n)/2)  1.
%e a(5)=2047 because the 5th even superperfect number is 4096 and (4096/2)1=2047.
%Y Cf. A019279, A061652, A133028.
%K nonn
%O 1,3
%A _Omar E. Pol_, Nov 07 2007
%E More terms from _Jinyuan Wang_, Mar 14 2020
