1,3

a(13) and a(14) have 153 and 179 digits respectively, and are too large to include here. - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jan 07 2008

O. E. Pol, Determinacion geometrica de los numeros primos y perfectos.

a(n)=A06152(n)/(2^n).

a(5)=128 because the 5th even superperfect number is 4096 and 2^5=32 and 4096/32=128.

A000043 := proc(n) op(n, [2, 3, 5, 7, 13, 17, 19, 31, 61, 89, 107, 127, 521, 607, 1279, 2203, 2281, 3217, 4253, 4423, 9689, 9941, 11213]) ; end: A061652 := proc(n) 2^(A000043(n)-1) ; end: A134710 := proc(n) A061652(n)/2^n ; end: seq(A134710(n), n=1..14) ; - R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jan 07 2008

Cf. A000396, A000668, A019279, A133028. Even superperfect numbers: A061652.

Adjacent sequences: A134707 A134708 A134709 this_sequence A134711 A134712 A134713

Sequence in context: A009595 A018493 A046035 this_sequence A009073 A012561 A012558

nonn

Omar E. Pol (info(AT)polprimos.com), Nov 07 2007

More terms from R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Jan 07 2008