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 A155718 #3 Mar 30 2012 17:34:33 %S A155718 2,-1,-1,9,-12,9,-47,32,32,-47,385,-420,280,-420,385,-3839,4354,-1460, %T A155718 -1460,4354,-3839,46081,-56490,26684,-11760,26684,-56490,46081, %U A155718 -645119,836296,-418936,92624,92624,-418936,836296,-645119,10321921,-14026824 %N A155718 Symmetrical form of A039683 using polynomials: p(x,n)=Product[x - (2*i), {i, 0, Floor[n/2]}]/x; t(n,m)=coefficients(p(x,n)+x^n*p(1/x,n)); t(n,m)=A039683(n,m)+A039683(n,n-m). %C A155718 Row sums are: %C A155718 {2, -2, 6, -30, 210, -1890, 20790, -270270, 4054050, -68918850, 1309458150,...}. %C A155718 The Stirling product form is: as even- odd factorization; %C A155718 Product[x-i,{i,0,n}]=Product[x-(2*i),{i,0,Floor[n/2]}]*Product[x-(2*i+1),{i,0,Floor[n/2]}] %F A155718 p(x,n)=Product[x - (2*i), {i, 0, Floor[n/2]}]/x; %F A155718 t(n,m)=coefficients(p(x,n)+x^n*p(1/x,n)); %F A155718 t(n,m)=A039683(n,m)+A039683(n,n-m). %e A155718 {2}, %e A155718 {-1, -1}, %e A155718 {9, -12, 9}, %e A155718 {-47, 32, 32, -47}, %e A155718 {385, -420, 280, -420, 385}, %e A155718 {-3839, 4354, -1460, -1460, 4354, -3839}, %e A155718 {46081, -56490, 26684, -11760, 26684, -56490, 46081}, %e A155718 {-645119, 836296, -418936, 92624, 92624, -418936, 836296, -645119}, %e A155718 {10321921, -14026824, 7562120, -2189376, 718368, -2189376, 7562120, -14026824, 10321921}, %e A155718 {-185794559, 262803366, -150102120, 46239920, -7606032, -7606032, 46239920, -150102120, 262803366, -185794559}, %e A155718 {3715891201, -5441863790, 3264920736, -1076561200, 221207888, -57731520, 221207888, -1076561200, 3264920736, -5441863790, 3715891201} %t A155718 Clear[p, x, n, b, a, b0]; %t A155718 p[x_, n_] := Product[x - (2*i), {i, 0, Floor[n/2]}]/x; %t A155718 Table[Expand[ CoefficientList[ExpandAll[p[x, n]], x] + Reverse[CoefficientList[ExpandAll[p[x, n]], x]]], {n, 0, 20, 2}]; %t A155718 Flatten[%] %Y A155718 A039683, A039757 %K A155718 uned,sign %O A155718 0,1 %A A155718 _Roger L. Bagula_, Jan 25 2009