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 A102588 #3 Mar 30 2012 18:36:44
%S A102588 1,2,4,6,12,22,34,58,112,186,320,574,954,1640,2926,5180,8524,14928,
%T A102588 25514,44994,77674,138446,233402,395832,704376,1223902,2134912,
%U A102588 3628044,6288414,10626878,19171626,32535060,57067872,97164452,169386950
%N A102588 Absolute row sums of triangle A102587, which is equal to the matrix inverse of triangle A094531 (the right-hand side of trinomial table A027907).
%o A102588 (PARI) {a(n)=local(A); A=matrix(n+1,n+1,r,c,if(r<c,0,polcoeff((1+x+x^2)^(r-1),r+c-2))); return(sum(k=0,n,abs((A^-1)[n+1,k+1])))}
%Y A102588 Cf. A094531, A102587.
%K A102588 nonn
%O A102588 0,2
%A A102588 _Paul D. Hanna_, Jan 22 2005