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 A189660 #6 Mar 30 2012 18:57:25 %S A189660 0,0,1,1,1,2,3,4,4,4,4,5,5,5,6,7,8,8,9,10,10,11,12,12,12,12,13,13,13, %T A189660 14,14,14,15,16,17,17,17,17,18,18,18,19,20,21,21,22,23,23,24,25,25,25, %U A189660 25,26,27,28,28,29,30,30,30,30,31,32,33,33,34,35,35,35,35,36,36,36,37,37,37,38,39,40,40 %N A189660 Partial sums of A064990. %C A189660 See A064990. %F A189660 s(n)=s([(n+2)/3])+s([(n+1)/3])+[n/3]-s([n/3]), where s(0)=0, s(1)=0. %t A189660 (See A064990.) %Y A189660 Cf. A064990, A189658, A189659. %K A189660 nonn %O A189660 1,6 %A A189660 _Clark Kimberling_, Apr 25 2011