A208909 Triangle of coefficients of polynomials u(n,x) jointly generated with A208930; see the Formula section.

1, 1, 2, 1, 6, 6, 1, 10, 20, 16, 1, 14, 42, 68, 44, 1, 18, 72, 172, 220, 120, 1, 22, 110, 344, 648, 696, 328, 1, 26, 156, 600, 1480, 2336, 2160, 896, 1, 30, 210, 956, 2900, 5984, 8128, 6608, 2448, 1, 34, 272, 1428, 5124, 12984, 23056, 27536, 19984

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)=(x+1)*u(n-1,x)+2x*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...10...20...16
1...14...42...68...44
First five polynomials u(n,x):
1
1 + 2x
1 + 6x + 6x^2
1 + 10x + 20x^2 + 16x^3
1 + 14x + 42x^2 + 68x^3 + 44x^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_] := (x + 1)*u[n - 1, x] + 2 x*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[%]    (* A208909 *)
Table[Expand[v[n, x]], {n, 1, z}]
cv = Table[CoefficientList[v[n, x], x], {n, 1, z}];
TableForm[cv]
Flatten[%]    (* A208930 *)

Crossrefs

Cf. A208909, A208510.

Sequence in context: A213615 A049019 A133314 * A229565 A259477 A208919

Adjacent sequences: A208906 A208907 A208908 * A208910 A208911 A208912

Keyword

nonn,tabl

Author

Clark Kimberling, Mar 04 2012

Status

approved