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 A209167 #10 Aug 07 2025 04:35:18 %S A209167 1,2,2,3,5,3,5,12,12,5,8,25,35,25,8,13,50,89,89,50,13,21,96,207,263, %T A209167 207,96,21,34,180,455,698,698,455,180,34,55,331,959,1719,2073,1719, %U A209167 959,331,55,89,600,1959,4011,5643,5643,4011,1959,600,89,144,1075 %N A209167 Triangle of coefficients of polynomials v(n,x) jointly generated with A209166; see the Formula section. %C A209167 Row n begins and ends with F(n+1), where F=A000045 (Fibonacci numbers). %C A209167 Alternating row sums: 1,0,1,0,1,0,1,0,1,0,1,0,1,0,... %C A209167 For a discussion and guide to related arrays, see A208510. %F A209167 u(n,x)=u(n-1,x)+(x+1)*v(n-1,x), %F A209167 v(n,x)=(x+1)*u(n-1,x)+x*v(n-1,x)+1, %F A209167 where u(1,x)=1, v(1,x)=1. %e A209167 First five rows: %e A209167 1 %e A209167 2 2 %e A209167 3 5 3 %e A209167 5 12 12 5 %e A209167 8 25 35 25 8 %e A209167 First three polynomials v(n,x): 1, 2 + 2*x, 3 + 5*x + 3*x^2. %t A209167 u[1, x_] := 1; v[1, x_] := 1; z = 16; %t A209167 u[n_, x_] := u[n - 1, x] + (x + 1)*v[n - 1, x]; %t A209167 v[n_, x_] := (x + 1)*u[n - 1, x] + x*v[n - 1, x] + 1; %t A209167 Table[Expand[u[n, x]], {n, 1, z/2}] %t A209167 Table[Expand[v[n, x]], {n, 1, z/2}] %t A209167 cu = Table[CoefficientList[u[n, x], x], {n, 1, z}]; %t A209167 TableForm[cu] %t A209167 Flatten[%] (* A209166 *) %t A209167 Table[Expand[v[n, x]], {n, 1, z}] %t A209167 cv = Table[CoefficientList[v[n, x], x], {n, 1, z}]; %t A209167 TableForm[cv] %t A209167 Flatten[%] (* A209167 *) %Y A209167 Cf. A209166, A208510. %K A209167 nonn,tabl %O A209167 1,2 %A A209167 _Clark Kimberling_, Mar 08 2012