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 A091860 #5 Mar 30 2012 18:39:22 %S A091860 1,1,2,3,4,4,6,5,6,6,8,6,8,8,8,7,8,8,10,8,10,10,10,8,10,10,10,10,10, %T A091860 10,10,9,10,10,12,10,12,12,12,10,12,12,12,12,12,12,12,10,12,12,12,12, %U A091860 12,12,12,12,12,12,12,12,12,12,12,11,12,12,14,12,14,14,14,12,14,14,14,14,14 %N A091860 a(1)=1, a(n)=sum(i=1,n-1,b(i)) where b(i)=0 if a(i) and a(n-i) are both even, b(i)=1 otherwise. %F A091860 n>1 a(2n)=a(n)+2; if n is a power of 2, a(2n+1)=1+a(2n); if n is the sum of 2 distinct power of 2, a(2n+1)=2+a(2n); a(2n+1)=a(2n) otherwise %o A091860 (PARI) an[1]=1;for(n=2,100,an[n]=sum(i=1,n-1,max(a(i)%2,a(n-i)%2))) %Y A091860 Cf. A018900, A072823. %K A091860 nonn %O A091860 1,3 %A A091860 _Benoit Cloitre_, Mar 16 2004