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 A130049 #3 Mar 30 2012 18:57:10 %S A130049 0,3,6,7,17,12,32,20,51,29,72,39,97,50,127,63,161,77,197,92,236,108, %T A130049 279,126,327,145,378,166,432,188,489,211,550,235,614,260,681,286,751, %U A130049 313,826,341,906,371,989,402,1074,435,1162,469,1252,504,1347,540,1445,577 %N A130049 An inductive sum sequence. %C A130049 Complement of A130048. The bisection sequences b(1),b(3),b(5),... and b(2),b(4),b(6),... are strictly increasing, but b(2n)<b(2n-1) for n>=3. %F A130049 A130049 is the sequence b defined inductively as follows: Let a(1)=1, a(2)=2, b(1)=0, b(2)=3; for n>=3, let x=Floor(n/2) and y=n-x+1. Then a(n)=least positive integer not among a(1),a(2),...,a(n-1), b(1),b(2),...b(n-1) and b(n)=a(1)+a(2)+...+a(x) if n is even, b(n)=a(y)+a(y+1)+...+a(n) if n is odd. %e A130049 (a(1),a(2),...,a(6))=(1,2,4,5,8,9), so x=4 and b(6)=1+2+4+5=12. %e A130049 (a(1),a(2),...,a(7))=(1,2,4,5,8,9,10), so y=4 and b(7)=5+8+9+10=32. %Y A130049 Cf. A130048, A130050, A130051. %K A130049 nonn %O A130049 1,2 %A A130049 _Clark Kimberling_, May 03 2007