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 A209171 #19 Jan 24 2020 03:33:34 %S A209171 1,3,2,6,8,3,12,25,19,5,24,68,77,40,8,48,172,259,201,80,13,96,416,782, %T A209171 806,478,154,21,192,976,2200,2825,2222,1067,289,34,384,2240,5888,9048, %U A209171 8857,5640,2277,532,55,768,5056,15184,27160,31787,25184,13483 %N A209171 Triangle of coefficients of polynomials v(n,x) jointly generated with A209170; see the Formula section. %C A209171 Column 1: Fibonacci numbers (A000045). %C A209171 Alternating row sums: 1,1,1,1,1,1,1,1,1,1,1,1,... %C A209171 For a discussion and guide to related arrays, see A208510. %C A209171 Subtriangle of (1, 2, -3/2, 1/2, 0, 0, 0, 0, 0, 0, 0, ...) DELTA (0, 2, -1/2, -1/2, 0, 0, 0, 0, 0, 0, 0, ...) where DELTA is the operator defined in A084938. - _Philippe Deléham_, Mar 10 2012 %F A209171 u(n,x) = u(n-1,x) + (x+1)*v(n-1,x), %F A209171 v(n,x) = (x+1)*u(n-1,x) + (x+1)*v(n-1,x)+1, %F A209171 where u(1,x)=1, v(1,x)=1. %F A209171 T(n,k) = 2*T(n-1,k) + T(n-1,k-1) + T(n-2,k-1) + T(n-2,k-2), T(1,0) = 1, T(2,0) = 3, T(2,1) = 2. - _Philippe Deléham_, Mar 10 2012 %F A209171 Sum_{k=0..n} T(n,k)*x^k = A000012(n), A003945(n-1), A007483(n-1) for x = -1, 0, 1 respectively. - _Philippe Deléham_, Mar 10 2012 %F A209171 G.f.: (-1-x-x*y)*x*y/(-1+2*x+x*y+x^2*y^2+x^2*y). - _R. J. Mathar_, Aug 12 2015 %e A209171 First five rows: %e A209171 1; %e A209171 3, 2; %e A209171 6, 8, 3; %e A209171 12, 25, 19, 5; %e A209171 24, 68, 77, 40, 8; %e A209171 First three polynomials v(n,x): %e A209171 1 %e A209171 3 + 2x %e A209171 6 + 8x + 3x^2. %e A209171 From _Philippe Deléham_, Mar 10 2012: (Start) %e A209171 Triangle (1, 2, -3/2, 1/2, 0, 0, ...) DELTA (0, 2, -1/2, -1/2, 0, 0, ...) begins (0 <= k <= n): %e A209171 1; %e A209171 1, 0; %e A209171 3, 2, 0; %e A209171 6, 8, 3, 0; %e A209171 12, 25, 19, 5, 0; %e A209171 24, 68, 77, 40, 8, 0; %e A209171 48, 172, 259, 201, 80, 13, 0; %e A209171 96, 416, 782, 806, 478, 154, 21, 0; (End) %t A209171 u[1, x_] := 1; v[1, x_] := 1; z = 16; %t A209171 u[n_, x_] := u[n - 1, x] + (x + 1)*v[n - 1, x]; %t A209171 v[n_, x_] := (x + 1)*u[n - 1, x] + (x + 1)*v[n - 1, x] + 1; %t A209171 Table[Expand[u[n, x]], {n, 1, z/2}] %t A209171 Table[Expand[v[n, x]], {n, 1, z/2}] %t A209171 cu = Table[CoefficientList[u[n, x], x], {n, 1, z}]; %t A209171 TableForm[cu] %t A209171 Flatten[%] (* A209170 *) %t A209171 Table[Expand[v[n, x]], {n, 1, z}] %t A209171 cv = Table[CoefficientList[v[n, x], x], {n, 1, z}]; %t A209171 TableForm[cv] %t A209171 Flatten[%] (* A209171 *) %Y A209171 Cf. A209170, A208510. %K A209171 nonn,tabl %O A209171 1,2 %A A209171 _Clark Kimberling_, Mar 08 2012