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 A130067 #3 Mar 31 2012 13:21:02 %S A130067 1,2,1,3,3,4,6,1,5,10,5,6,15,15,7,21,35,8,28,70,1,9,36,126,9,10,45, %T A130067 210,45,11,55,330,165,12,66,495,495,13,78,715,1287,14,91,1001,3003,15, %U A130067 105,1365,6435,16,120,1820,12870,1,17,136,2380,24310,17,18,153,3060,43758 %N A130067 Binomial coefficients binomial(m,2^k) where m>=1 and 1<=2^k<=m. %C A130067 Provided m and k are given, the sequence index n is n=A001855(m)+k+1. Ordered by m as rows and k as columns the sequence forms a sort of a logarithmically distorted triangle. a(n) is odd if and only if A030308(n)=1. %F A130067 a(n)=binomial(m,2^k), where m=max(j|A001855(j)<n) and k=n-1-A001855(m). %e A130067 a(6)=4 since n=6 gives m=4, k=0 and so binomial(4,2^0)=4. %e A130067 a(20)=70 since n=20 gives m=8, k=2 and so binomial(8,2^2)=70. %Y A130067 Cf. A130068, A065040, A001855, A030308. %K A130067 nonn %O A130067 1,2 %A A130067 _Hieronymus Fischer_, May 05 2007, Sep 10 2007