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 A151689 #2 Mar 30 2012 16:51:05
%S A151689 2,6,4,6,16,16,6,6,16,16,18,40,50,30,8,6,16,16,18,40,50,30,20,40,50,
%T A151689 54,100,142,112,48,10,6,16,16,18,40,50,30,20,40,50,54,100,142,112,48,
%U A151689 22,40,50,54,100,142,112,72,102,142,160,256,386,368,210,70,12,6,16,16,18,40,50
%N A151689 a(n) = sum_{k >= 1} 2^wt(k) * binomial(wt(n+k),k).
%p A151689 wt := proc(n) local w,m,i;
%p A151689 w := 0; m := n; while m > 0 do i := m mod 2; w := w+i; m := (m-i)/2; od; w; end:
%p A151689 f := n->add( 2^k*binomial(wt(n+k),k),k=1..20 );
%Y A151689 Cf. A151685, A151690.
%K A151689 nonn
%O A151689 0,1
%A A151689 _N. J. A. Sloane_, Jun 04 2009