A208919 Triangle of coefficients of polynomials u(n,x) jointly generated with A208920; see the Formula section.

1, 1, 2, 1, 6, 6, 1, 12, 20, 14, 1, 20, 44, 66, 38, 1, 30, 80, 190, 208, 94, 1, 42, 130, 430, 678, 622, 246, 1, 56, 196, 840, 1708, 2380, 1852, 622, 1, 72, 280, 1484, 3668, 6888, 7928, 5338, 1606, 1, 90, 384, 2436, 7056, 16716, 25344, 25650, 15336

Offset

1,3

Comments

For a discussion and guide to related arrays, see A208510.

Links

Table of n, a(n) for n=1..54.

Formula

u(n,x)=u(n-1,x)+2x*v(n-1,x),

v(n,x)=2x*u(n-1,x)+(x+1)*v(n-1,x)+1,

where u(1,x)=1, v(1,x)=1.

Example

First five rows:
1
1...2
1...6....6
1...12...20...14
1...20...44...66...38
First five polynomials u(n,x):
1
1 + 2x
1 + 6x + 6x^2
1 + 12x + 20x^2 + 14x^3
1 + 20x + 44x^2 + 66x^3 + 38x^4

Mathematica

u[1, x_] := 1; v[1, x_] := 1; z = 16;
u[n_, x_] := u[n - 1, x] + 2 x*v[n - 1, x];
v[n_, x_] := 2 x*u[n - 1, x] + (x + 1)*v[n - 1, x] + 1;
Table[Expand[u[n, x]], {n, 1, z/2}]
Table[Expand[v[n, x]], {n, 1, z/2}]
cu = Table[CoefficientList[u[n, x], x], {n, 1, z}];
TableForm[cu]
Flatten[%]    (* A208919 *)
Table[Expand[v[n, x]], {n, 1, z}]
cv = Table[CoefficientList[v[n, x], x], {n, 1, z}];
TableForm[cv]
Flatten[%]    (* A208920 *)

Crossrefs

Cf. A208920, A208510.

Sequence in context: A208909 A229565 A259477 * A347580 A259569 A046651

Adjacent sequences: A208916 A208917 A208918 * A208920 A208921 A208922

Keyword

nonn,tabl

Author

Clark Kimberling, Mar 04 2012

Status

approved