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 A209578 #7 Mar 30 2012 18:58:15 %S A209578 1,3,1,5,3,1,9,8,4,1,15,19,13,5,1,25,41,36,19,6,1,41,84,90,60,26,7,1, %T A209578 67,165,210,169,92,34,8,1,109,315,465,439,287,133,43,9,1,177,588,990, %U A209578 1073,818,454,184,53,10,1,287,1079,2043,2502,2178,1405,681,246 %N A209578 Triangle of coefficients of polynomials v(n,x) jointly generated with A209577; see the Formula section. %C A209578 Alternating row sums: 1,0,2,1,3,2,4,3,5,4,... (A028242). %C A209578 For a discussion and guide to related arrays, see A208510. %F A209578 u(n,x)=x*u(n-1,x)+v(n-1,x), %F A209578 v(n,x)=(x+1)*u(n-1,x)+v(n-1,x)+1, %F A209578 where u(1,x)=1, v(1,x)=1. %e A209578 First five rows: %e A209578 1 %e A209578 1...1 %e A209578 3...2....1 %e A209578 5...6....3....1 %e A209578 9...13...10...4...1 %e A209578 First three polynomials v(n,x): 1, 1 + x , 3 + 2x + x^2. %t A209578 u[1, x_] := 1; v[1, x_] := 1; z = 16; %t A209578 u[n_, x_] := x*u[n - 1, x] + v[n - 1, x]; %t A209578 v[n_, x_] := (x + 1)*u[n - 1, x] + v[n - 1, x] + 1; %t A209578 Table[Expand[u[n, x]], {n, 1, z/2}] %t A209578 Table[Expand[v[n, x]], {n, 1, z/2}] %t A209578 cu = Table[CoefficientList[u[n, x], x], {n, 1, z}]; %t A209578 TableForm[cu] %t A209578 Flatten[%] (* A209577 *) %t A209578 Table[Expand[v[n, x]], {n, 1, z}] %t A209578 cv = Table[CoefficientList[v[n, x], x], {n, 1, z}]; %t A209578 TableForm[cv] %t A209578 Flatten[%] (* A209578 *) %Y A209578 Cf. A209577, A208510. %K A209578 nonn,tabl %O A209578 1,2 %A A209578 _Clark Kimberling_, Mar 11 2012