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 A056593 #4 Mar 31 2012 13:20:04 %S A056593 1,2,4,10,32,132,692,4620,39352,427572,5918992,104375880,2344751912, %T A056593 67092113592,2444702271152,113425536387240,6700361921561152, %U A056593 503909247633965712,48243317287320644752,5879293173259041034800 %N A056593 Row sums of unsigned triangle A056588. %F A056593 a(n)= sum(((-1)^(floor((m+1)/2)))*A056588(n, m), m=0..n), n >= 0. %Y A056593 Cf. A000045, A056588, A056592. %K A056593 nonn,easy %O A056593 0,2 %A A056593 _Wolfdieter Lang_ Jul 10 2000