A207610 Triangle of coefficients of polynomials u(n,x) jointly generated with A207611; see the Formula section.

1, 2, 4, 1, 7, 3, 1, 12, 7, 3, 1, 20, 15, 8, 3, 1, 33, 30, 19, 9, 3, 1, 54, 58, 42, 23, 10, 3, 1, 88, 109, 89, 55, 27, 11, 3, 1, 143, 201, 182, 125, 69, 31, 12, 3, 1, 232, 365, 363, 273, 166, 84, 35, 13, 3, 1, 376, 655, 709, 579, 383, 212, 100, 39, 14, 3, 1, 609

Offset: 1

Author

Clark Kimberling, Feb 19 2012

Keywords

• nonn
• tabf

Examples

			First five rows:
1
2
4...1
7...3...1
12...7...3...1
		

Crossrefs

Cf. A207611.

Cf. A000071 (column 1), A023610 (column 2).

Programs

Mathematica

u[1, x_] := 1; v[1, x_] := 1; z = 16;
u[n_, x_] := u[n - 1, x] + v[n - 1, x]
v[n_, x_] := u[n - 1, x] + x*v[n - 1, x] + 1
Table[Factor[u[n, x]], {n, 1, z}]
Table[Factor[v[n, x]], {n, 1, z}]
cu = Table[CoefficientList[u[n, x], x], {n, 1, z}];
TableForm[cu]
Flatten[%]    (* A207610 *)
Table[Expand[v[n, x]], {n, 1, z}]
cv = Table[CoefficientList[v[n, x], x], {n, 1, z}];
TableForm[cv]
Flatten[%]    (* A207611 *)

Python

from sympy import Poly
from sympy.abc import x
def u(n, x): return 1 if n==1 else u(n - 1, x) + v(n - 1, x)
def v(n, x): return 1 if n==1 else u(n - 1, x) + x*v(n - 1, x) + 1
def a(n): return Poly(u(n, x), x).all_coeffs()[::-1]
for n in range(1, 13): print(a(n)) # Indranil Ghosh, May 28 2017

Formula

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