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 A050611 #4 May 01 2014 02:49:07
%S A050611 1,3,6,21,35,126,273,987,1598,5781,12549,45402,76657,277347,602070,
%T A050611 2178309,3524579,12752046,27682401,100155867,169104754,611826747,
%U A050611 1328165979,4805349654,7782268225,28156510947,61122728166,221144107989
%N A050611 Sum_{i=0..n} (C(n,i) mod 2)*Fibonacci(2i+1) = FL(n+1)Product(L(2^i)^bit(n,i),i=0..).
%Y A050611 Second row of A050609, second column of A050610.
%K A050611 nonn
%O A050611 0,2
%A A050611 _Antti Karttunen_, Oct 24 1999