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 A099893 #7 Mar 30 2012 18:36:43
%S A099893 0,1,3,0,7,0,0,0,15,0,0,0,0,0,0,0,31,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,63,
%T A099893 0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,0,127
%N A099893 XOR BINOMIAL transform of A006068 (inverse Gray code).
%C A099893 See A099884 for the definitions of the XOR BINOMIAL transform and the XOR difference triangle.
%F A099893 a(2^n) = 2^(n+1)-1 for n>0, with a(0)=0 and a(k)=0 otherwise. a(n) = SumXOR_{i=0..n} (C(n, i)mod 2)*A006068(n-i) and SumXOR is summation under XOR.
%o A099893 (PARI) {a(n)=local(B);B=0;for(i=0,n,B=bitxor(B,binomial(n,i)%2*A006068(n-i) ));B}
%Y A099893 Cf. A099884, A006068, A099894.
%K A099893 nonn,mult
%O A099893 0,3
%A A099893 _Paul D. Hanna_, Oct 29 2004