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 A256490 #5 May 04 2015 02:10:14
%S A256490 8,7,9,7,13,2,10,7,13,2,14,8,7,2,11,7,13,2,14,8,7,2,15,8,7,9,7,14,1,2,
%T A256490 12,7,13,2,14,8,7,2,15,8,7,9,7,14,1,2,16,8,7,9,7,14,1,10,7,14,1,15,8,
%U A256490 7,1,2,13,7,13,2,14,8,7,2,15,8,7,9,7,14,1,2,16,8,7,9,7,14,1,10,7,14,1,15,8,7,1
%N A256490 First differences of A257512: a(n) = A257512(n+1) - A257512(n).
%C A256490 It seems that for all n >= 1, Sum_{k=1 .. 2^n} a(k) = 2^(n+3) - 1 = A000225(n+3).
%H A256490 Antti Karttunen, <a href="/A256490/b256490.txt">Table of n, a(n) for n = 1..16384</a>
%F A256490 a(n) = A257512(n+1) - A257512(n).
%o A256490 (Scheme) (define (A256490 n) (- (A257512 (+ n 1)) (A257512 n)))
%Y A256490 Cf. A000225, A257512, A256489.
%K A256490 nonn
%O A256490 1,1
%A A256490 _Antti Karttunen_, May 03 2015