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 A210201 #4 Mar 30 2012 18:58:16 %S A210201 1,3,6,3,11,10,6,19,27,23,12,32,62,73,52,24,53,132,193,187,116,48,87, %T A210201 266,468,552,462,256,96,142,517,1061,1482,1495,1112,560,192,231,978, %U A210201 2297,3688,4369,3896,2624,1216,384,375,1813,4797,8703,11758 %N A210201 Triangle of coefficients of polynomials u(n,x) jointly generated with A210202; see the Formula section. %C A210201 Row sums: 3^(n-1) %C A210201 For a discussion and guide to related arrays, see A208510. %F A210201 u(n,x)=u(n-1,x)+v(n-1,x)+1, %F A210201 v(n,x)=(x+1)*u(n-1,x)+2x*v(n-1,x)+1, %F A210201 where u(1,x)=1, v(1,x)=1. %e A210201 First five rows: %e A210201 1 %e A210201 3 %e A210201 6....3 %e A210201 11...10...6 %e A210201 19...27...23...12 %e A210201 First three polynomials u(n,x): 1, 3, 6 + 3x. %t A210201 u[1, x_] := 1; v[1, x_] := 1; z = 16; %t A210201 u[n_, x_] := u[n - 1, x] + v[n - 1, x] + 1; %t A210201 v[n_, x_] := (x + 1)*u[n - 1, x] + 2 x*v[n - 1, x] + 1; %t A210201 Table[Expand[u[n, x]], {n, 1, z/2}] %t A210201 Table[Expand[v[n, x]], {n, 1, z/2}] %t A210201 cu = Table[CoefficientList[u[n, x], x], {n, 1, z}]; %t A210201 TableForm[cu] %t A210201 Flatten[%] (* A210201 *) %t A210201 Table[Expand[v[n, x]], {n, 1, z}] %t A210201 cv = Table[CoefficientList[v[n, x], x], {n, 1, z}]; %t A210201 TableForm[cv] %t A210201 Flatten[%] (* A210202 *) %Y A210201 Cf. A210202, A208510. %K A210201 nonn,tabf %O A210201 1,2 %A A210201 _Clark Kimberling_, Mar 18 2012