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 A209703 #5 Mar 30 2012 18:58:15 %S A209703 1,0,2,0,3,3,0,4,6,5,0,5,10,14,8,0,6,15,28,28,13,0,7,21,48,66,55,21,0, %T A209703 8,28,75,129,149,104,34,0,9,36,110,225,326,319,193,55,0,10,45,154,363, %U A209703 626,774,661,352,89,0,11,55,208,553,1099,1625,1761,1332,634 %N A209703 Triangle of coefficients of polynomials u(n,x) jointly generated with A209704; see the Formula section. %C A209703 For n>1, row n begins with 0, has second term n, and ends with F(n+1), where F=A000045 (Fibonacci numbers); for n>2, column 2 consists of triangular numbers. %C A209703 Row sums: A098790. %C A209703 Alternating row sums: 1,-2,0,-3,-1,-4,-3,-5,-3,-6,,... %C A209703 For a discussion and guide to related arrays, see A208510. %F A209703 u(n,x)=x*u(n-1,x)+x*v(n-1,x), %F A209703 v(n,x)=(x+1)*u(n-1,x)+v(n-1,x)+1, %F A209703 where u(1,x)=1, v(1,x)=1. %e A209703 First five rows: %e A209703 1 %e A209703 0...2 %e A209703 0...3....3 %e A209703 0...4....6...5 %e A209703 0...5...10...14...8 %e A209703 First three polynomials v(n,x): 1, 2x, 3x + 3x^2. %t A209703 u[1, x_] := 1; v[1, x_] := 1; z = 16; %t A209703 u[n_, x_] := x*u[n - 1, x] + x*v[n - 1, x]; %t A209703 v[n_, x_] := (x + 1)*u[n - 1, x] + v[n - 1, x] + 1; %t A209703 Table[Expand[u[n, x]], {n, 1, z/2}] %t A209703 Table[Expand[v[n, x]], {n, 1, z/2}] %t A209703 cu = Table[CoefficientList[u[n, x], x], {n, 1, z}]; %t A209703 TableForm[cu] %t A209703 Flatten[%] (* A209703 *) %t A209703 Table[Expand[v[n, x]], {n, 1, z}] %t A209703 cv = Table[CoefficientList[v[n, x], x], {n, 1, z}]; %t A209703 TableForm[cv] %t A209703 Flatten[%] (* A209704 *) %Y A209703 Cf. A209704, A208510. %K A209703 nonn,tabl %O A209703 1,3 %A A209703 _Clark Kimberling_, Mar 12 2012