This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A134705 #9 Mar 03 2017 17:33:36 %S A134705 3,7,62,508,1048448,134216704,1073739776,9007199250546688, %T A134705 5192296858534827626278696515534848, %U A134705 187072209578355573530071658285452771612302071824384 %N A134705 a(n) = n-th perfect number divided by 2^n. %H A134705 Omar E. Pol, <a href="http://www.polprimos.com">Determinacion geometrica de los numeros primos y perfectos</a>. %F A134705 a(n)=A000396(n)/(2^n). %e A134705 a(3)=62 because the 3rd perfect number is 496 and 2^3=8 and 496/8=62. %p A134705 perfp := [1,2,4,6,12,16,18,30,60,88,106,126,520,606,1278,2202,2280,3216,4252] : A000396 := proc(n) global perfp ; 2^op(n,perfp)*(2^(op(n,perfp)+1)-1) ; end: A134705 := proc(n) A000396(n)/2^n ; end: seq(A134705(n),n=1..12) ; # _R. J. Mathar_ %Y A134705 Cf. A000396, A133028. %K A134705 nonn %O A134705 1,1 %A A134705 _Omar E. Pol_, Nov 07 2007 %E A134705 More terms from _R. J. Mathar_, Jan 07 2008