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 A210551 #25 May 18 2020 06:17:16 %S A210551 1,3,1,5,6,1,7,15,10,1,9,28,35,15,1,11,45,84,70,21,1,13,66,165,210, %T A210551 126,28,1,15,91,286,495,462,210,36,1,17,120,455,1001,1287,924,330,45, %U A210551 1,19,153,680,1820,3003,3003,1716,495,55,1,21,190,969,3060,6188 %N A210551 Triangle of coefficients of polynomials v(n,x) jointly generated with A172431; see the Formula section. %C A210551 Row sums: -1+odd-indexed Fibonacci numbers %C A210551 Alternating row sums: 1,2,0,1,2,0,1,2,0,... %C A210551 For a discussion and guide to related arrays, see A208510. %F A210551 u(n,x)=x*u(n-1,x)+x*v(n-1,x)+1, %F A210551 v(n,x)=u(n-1,x)+(x+1)*v(n-1,x)+1 %F A210551 where u(1,x)=1, v(1,x)=1. %e A210551 From _Paul Weisenhorn_, May 17 2020 : (Start) %e A210551 First five rows of v(n.x): %e A210551 1 %e A210551 3 1 %e A210551 5 6 1 %e A210551 7 15 10 1 %e A210551 9 28 35 15 1 %e A210551 First three polynomials v(n,x): 1, 3 + x, 5 + 6x + x^2. (End) %e A210551 From _Paul Weisenhorn_, May 14 2020: (Start) %e A210551 First five rows of u(n,x): %e A210551 1 %e A210551 1 2 %e A210551 1 4 3 %e A210551 1 6 10 4 %e A210551 1 8 21 20 5 %e A210551 First three polynomials u(n,x): 1, 1 + 2x, 1 + 4x + 3x^2. (End) %t A210551 u[1, x_] := 1; v[1, x_] := 1; z = 16; %t A210551 u[n_, x_] := x*u[n - 1, x] + x*v[n - 1, x] + 1; %t A210551 v[n_, x_] := u[n - 1, x] + (x + 1)*v[n - 1, x] + 1; %t A210551 Table[Expand[u[n, x]], {n, 1, z/2}] %t A210551 Table[Expand[v[n, x]], {n, 1, z/2}] %t A210551 cu = Table[CoefficientList[u[n, x], x], {n, 1, z}]; %t A210551 TableForm[cu] %t A210551 Flatten[%] (* A172431 *) %t A210551 Table[Expand[v[n, x]], {n, 1, z}] %t A210551 cv = Table[CoefficientList[v[n, x], x], {n, 1, z}]; %t A210551 TableForm[cv] %t A210551 Flatten[%] (* A210551 *) %Y A210551 Cf. A172431, A208510. %K A210551 nonn,tabl %O A210551 1,2 %A A210551 _Clark Kimberling_, Mar 22 2012