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 A210223 #5 Mar 30 2012 18:58:16 %S A210223 1,2,1,2,5,1,2,7,10,1,2,7,22,17,1,2,7,26,57,26,1,2,7,26,89,126,37,1,2, %T A210223 7,26,97,266,247,50,1,2,7,26,97,346,695,442,65,1,2,7,26,97,362,1127, %U A210223 1618,737,82,1,2,7,26,97,362,1319,3298,3425,1162,101,1,2,7,26 %N A210223 Triangle of coefficients of polynomials u(n,x) jointly generated with A210224; see the Formula section. %C A210223 Limiting row: A001075 %C A210223 For a discussion and guide to related arrays, see A208510. %F A210223 u(n,x)=x*u(n-1,x)+v(n-1,x)+1, %F A210223 v(n,x)=2x*u(n-1,x)+x*v(n-1,x)+1, %F A210223 where u(1,x)=1, v(1,x)=1. %e A210223 First five rows: %e A210223 1 %e A210223 2...1 %e A210223 2...5...1 %e A210223 2...7...10...1 %e A210223 2...7...22...17...1 %e A210223 First three polynomials u(n,x): 1, 2 + x, 2 + 5x + x^2. %t A210223 u[1, x_] := 1; v[1, x_] := 1; z = 16; %t A210223 u[n_, x_] := x*u[n - 1, x] + v[n - 1, x] + 1; %t A210223 v[n_, x_] := 2 x*u[n - 1, x] + x*v[n - 1, x] + 1; %t A210223 Table[Expand[u[n, x]], {n, 1, z/2}] %t A210223 Table[Expand[v[n, x]], {n, 1, z/2}] %t A210223 cu = Table[CoefficientList[u[n, x], x], {n, 1, z}]; %t A210223 TableForm[cu] %t A210223 Flatten[%] (* A210223 *) %t A210223 Table[Expand[v[n, x]], {n, 1, z}] %t A210223 cv = Table[CoefficientList[v[n, x], x], {n, 1, z}]; %t A210223 TableForm[cv] %t A210223 Flatten[%] (* A210224 *) %Y A210223 Cf. A210224, A208510. %K A210223 nonn,tabl %O A210223 1,2 %A A210223 _Clark Kimberling_, Mar 20 2012