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 A088504 #7 Mar 29 2015 12:00:32
%S A088504 0,0,2,0,14,20,32,0,254,492,932,1584,3104,4160,8192,0,65534,131036,
%T A088504 261836,521968,1038884,2044440,4029984,7607296,15306272,27305280,
%U A088504 53360192,77448960,201334784,268451840,536870912,0,4294967294
%N A088504 Sum of even entries in row n of Pascal's triangle.
%C A088504 a(n) = 0 iff n = 2^k - 1.
%C A088504 A088560(n) = A088504(n) iff n = 2^k - 2, k>1. A088560(n) > A088504(n) iff n = 2^k - 1.
%F A088504 A088504(n) + A088560(n) = 2^n. A088504(n) - A088560(n) = A085814(n).
%t A088504 f[n_] := Plus @@ Select[ Table[ Binomial[n, i], {i, 0, n}], EvenQ[ # ] & ]; Table[ f[n], {n, 0, 35}] (* _Robert G. Wilson v_, Nov 19 2003 *)
%Y A088504 Cf. A048967.
%K A088504 nonn
%O A088504 0,3
%A A088504 Yuval Dekel (dekelyuval(AT)hotmail.com), Nov 18 2003
%E A088504 Edited and extended by _Robert G. Wilson v_ and _Ray Chandler_, Nov 19 2003