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 A129101 #5 Jun 14 2017 00:27:58 %S A129101 1,2,6,24,136,1162,15702,346768,12836904,814033666,90074891654, %T A129101 17659668432744,6211830230882472,3960850942657072026, %U A129101 4617438765658479411542,9912250203901899238148640 %N A129101 Column 1 of triangle A129100; also equals column 0 of the matrix square of A129100. %F A129101 a(n) = A129094(n+1) - A129093(n); a(n) = A030067(2^(n+1)+2^n-1) - A030067(2^(n+1)-3) for n>=0 where A030067 is the semi-Fibonacci numbers. %o A129101 (PARI) a(n)=local(A=Mat(1),B);for(m=1,n+2,B=matrix(m,m);for(r=1,m,for(c=1,r, if(r==c || r==1 || r==2,B[r,c]=1,if(c==1,B[r,1]=sum(i=1,r-1,A[r-1,i]), B[r,c]=(A^(2^(c-1)))[r-c+1,1])); )); A=B); return(A[n+2,2]) %Y A129101 Cf. A129100 (triangle); A129092 (column 0), A129102 (column 2), A129103 (column 3). %K A129101 nonn %O A129101 0,2 %A A129101 _Paul D. Hanna_, Mar 29 2007