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 A187017 #7 Mar 30 2012 17:35:24 %S A187017 1,2,5,2,3,8,14,8,3,4,11,20,30,20,11,4,5,14,26,40,55,40,26,14,5,6,17, %T A187017 32,50,70,91,70,50,32,17,6,7,20,38,60,85,112,140,112,85,60,38,20,7,8, %U A187017 23,44,70,100,133,168,204,168,133,100,70,44,23,8,9,26,50,80,115,154,196,240,285,240,196,154,115,80,50,26,9 %N A187017 Array where the n-th row is the expansion of (1+2*x+...+n*x^(n-1)) * (n+(n-1)*x+...+x^(n-1)). %e A187017 The table starts: %e A187017 1 %e A187017 2 5 2 %e A187017 3 8 14 8 3 %e A187017 4 11 20 30 20 11 4 %o A187017 (PARI) al(n)=Vec(sum(k=1,n,k*x^(k-1))*sum(k=1,n,k*x^(n-k))) %Y A187017 Cf. A005408(row lengths), A000537(row sums), A115262(a rearrangement), A000330(central diagonal). %K A187017 nonn,tabf,easy %O A187017 1,2 %A A187017 _Franklin T. Adams-Watters_, Mar 02 2011