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 A209162 #5 Mar 30 2012 18:58:15 %S A209162 1,2,1,4,6,3,7,18,17,5,11,42,63,42,11,16,85,183,195,103,21,22,156,452, %T A209162 678,558,240,43,29,266,994,1966,2252,1510,553,85,37,428,2002,5012, %U A209162 7494,6946,3929,1246,171,46,657,3762,11586,21702,26060,20265,9909 %N A209162 Triangle of coefficients of polynomials u(n,x) jointly generated with A209163; see the Formula section. %C A209162 Alternating row sums: 1,1,1,1,1,1,1,1,1,1,1,1,1,1,... %C A209162 For a discussion and guide to related arrays, see A208510. %F A209162 u(n,x)=u(n-1,x)+(x+1)*v(n-1,x), %F A209162 v(n,x)=2x*u(n-1,x)+(x+1)*v(n-1,x)+1, %F A209162 where u(1,x)=1, v(1,x)=1. %e A209162 First five rows: %e A209162 1 %e A209162 2....1 %e A209162 4....6....3 %e A209162 7....18...17...5 %e A209162 11...42...63...42...11 %e A209162 First three polynomials v(n,x): 1, 2 + x, 4 + 6x + 3x^2. %t A209162 u[1, x_] := 1; v[1, x_] := 1; z = 16; %t A209162 u[n_, x_] := u[n - 1, x] + (x + 1)*v[n - 1, x]; %t A209162 v[n_, x_] := 2 x*u[n - 1, x] + (x + 1)*v[n - 1, x] + 1; %t A209162 Table[Expand[u[n, x]], {n, 1, z/2}] %t A209162 Table[Expand[v[n, x]], {n, 1, z/2}] %t A209162 cu = Table[CoefficientList[u[n, x], x], {n, 1, z}]; %t A209162 TableForm[cu] %t A209162 Flatten[%] (* A209162 *) %t A209162 Table[Expand[v[n, x]], {n, 1, z}] %t A209162 cv = Table[CoefficientList[v[n, x], x], {n, 1, z}]; %t A209162 TableForm[cv] %t A209162 Flatten[%] (* A209163 *) %Y A209162 Cf. A209163, A208510. %K A209162 nonn,tabl %O A209162 1,2 %A A209162 _Clark Kimberling_, Mar 07 2012