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 A175913 #2 Mar 31 2012 20:01:58
%S A175913 1,4,25,190,1159,15692,111381,1416474,24608235,291074808,5162763209,
%T A175913 125052555486,2198977618351,28389504497340,487294161504141,
%U A175913 11589641752262546,395151697837143155,13197172619557324880
%N A175913 Convert to decimal the number resulting from performing binary xnor on the corresponding digits in the left and right binary concatenations of the integers one to n.
%t A175913 frombinrep[x_] := FromDigits[Flatten[Table[Table[If[OddQ[ n], 1, 0], {d, 1, x[[n]]}], {n, 1, Length[x]}]], 2]
%t A175913 repcount[x_] := Length/@Split[x]
%t A175913 l = {}; r = {}; Table[d = IntegerDigits[x, 2]; l = Flatten[{l, d}]; r = Flatten[{d, r}]; frombinrep[ repcount[EvenQ[l + r]]], {x, 1, DESIRED NUMBER OF TERMS HERE}]
%Y A175913 Cf. A047778, A098780
%K A175913 base,easy,nonn
%O A175913 1,2
%A A175913 _Dylan Hamilton_, Oct 14 2010