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 A138870 #14 Apr 21 2023 13:01:01 %S A138870 2,4,16,64,409,655,262,107,115,309,811,850,343,265,520,737,223,129, %T A138870 953,142,239,173,140,215,224,201,427,268,260,256,373,870,647,206,407, %U A138870 311,637,218,462,629,149,610,157,622,101,849,158 %N A138870 First 3 digits of n-th even superperfect number A061652(n). %C A138870 Also, first 3 digits of n-th superperfect number A019279(n), if there are no odd superperfect numbers. %Y A138870 Cf. A019279, A061652, A138864, A138867, A138871, A138872, A138876. %K A138870 nonn,base,more %O A138870 1,1 %A A138870 _Omar E. Pol_, Apr 02 2008 %E A138870 a(12)-a(31) from _R. J. Mathar_, Feb 05 2010 %E A138870 a(32)-a(41) from _Max Alekseyev_, Feb 11 2012 %E A138870 a(42)-a(47) from _Jinyuan Wang_, Mar 14 2020