A208520 Triangle of coefficients of polynomials u(n,x) jointly generated with A208521; see the Formula section.

1, 1, 1, 1, 3, 2, 1, 6, 6, 2, 1, 10, 12, 10, 4, 1, 15, 20, 30, 20, 4, 1, 21, 30, 70, 60, 28, 8, 1, 28, 42, 140, 140, 112, 56, 8, 1, 36, 56, 252, 280, 336, 224, 72, 16, 1, 45, 72, 420, 504, 840, 672, 360, 144, 16, 1, 55, 90, 660, 840, 1848, 1680, 1320, 720, 176

Offset: 1

Author

Clark Kimberling, Feb 28 2012

Keywords

• nonn
• tabl

Examples

			First five rows:
1
1...1
1...3...2
1...6...6...2
1...10...12...10...4
First five polynomials u(n,x):
1
1 + x
1 + 3x + 2x^2
1 + 6x + 6x^2 + 2x^3
1 + 10x + 12x^2 + 10x^3 + 4x^4
		

Crossrefs

Cf. A208521.

Programs

Mathematica

u[1, x_] := 1; v[1, x_] := 1; z = 16;
u[n_, x_] := u[n - 1, x] + x*v[n - 1, x];
v[n_, x_] := 2 x*u[n - 1, 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[%]    (* A208520 *)
Table[Expand[v[n, x]], {n, 1, z}]
cv = Table[CoefficientList[v[n, x], x], {n, 1, z}];
TableForm[cv]
Flatten[%]    (* A208521 *)

Formula

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

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

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