A209693 Triangle of coefficients of polynomials u(n,x) jointly generated with A209694; see the Formula section.

1, 0, 2, 0, 3, 3, 0, 4, 9, 4, 0, 5, 17, 19, 5, 0, 6, 27, 49, 34, 6, 0, 7, 39, 98, 115, 55, 7, 0, 8, 53, 170, 284, 236, 83, 8, 0, 9, 69, 269, 585, 706, 440, 119, 9, 0, 10, 87, 399, 1070, 1706, 1568, 763, 164, 10, 0, 11, 107, 564, 1799, 3577, 4395, 3193, 1250, 219

Offset

1,3

Comments

Alternating row sums are periodic.

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

Links

Table of n, a(n) for n=1..65.

Formula

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

v(n,x)=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
0...2
0...2...4
0...1...8...8
0...1...5...24...16
First three polynomials v(n,x): 1, 2x, 2x + 4x^2.

Mathematica

u[1, x_] := 1; v[1, x_] := 1; z = 16;
u[n_, x_] := x*u[n - 1, x] + x*v[n - 1, x];
v[n_, 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[%]   (* A209693 *)
Table[Expand[v[n, x]], {n, 1, z}]
cv = Table[CoefficientList[v[n, x], x], {n, 1, z}];
TableForm[cv]
Flatten[%]   (* A209694 *)

Crossrefs

Cf. A209694, A208510.

Sequence in context: A127952 A171307 A372817 * A154344 A134409 A327878

Adjacent sequences: A209690 A209691 A209692 * A209694 A209695 A209696

Keyword

nonn,tabl

Author

Clark Kimberling, Mar 12 2012

Status

approved