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 A138835 #3 Mar 30 2012 17:39:33 %S A138835 4,64,65536,1073741824,309485009821345068724781056, %T A138835 85070591730234615865843651857942052864 %N A138835 Bisection of even superperfect numbers A061652. %C A138835 Also, bisection of superperfect numbers A019279, if there are no odd superperfect numbers. %C A138835 Next terms have 183, 663 and more digits and are therefore not listed. - _R. J. Mathar_, May 22 2008 %Y A138835 Cf. A019279, A061652, A099057, A099058, A134721, A134722, A138834. %K A138835 nonn %O A138835 1,1 %A A138835 _Omar E. Pol_, Apr 06 2008