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 A156261 #4 Jun 02 2025 01:21:02 %S A156261 0,1,1,1,2,3,3,4,4,5,6,6,6,7,7,8,9,9,9,10,10,10,11,12,12,13,13,13,14, %T A156261 14,14,15,16,16,17,17,17,18,19,19,20,21,21,22,23,23,23,24,24,25,25,25, %U A156261 26,27,27,27,28,28,29,30,30,31,31,32,33,33,34,34,34,35,35,35,36,37,37,38 %N A156261 a(n)=n/2+(1/2)*sum(k=1,n,A000002(A078649(k)+2)-A000002(A078649(k))). %C A156261 A000002(A078649(n))=A000002(A078649(n)+1) %K A156261 nonn %O A156261 1,5 %A A156261 _Benoit Cloitre_, Feb 07 2009