cp's OEIS Frontend

This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.

A208508 Triangle of coefficients of polynomials u(n,x) jointly generated with A208509; see the Formula section.

Original entry on oeis.org

1, 1, 1, 1, 4, 1, 9, 1, 1, 16, 6, 1, 25, 20, 1, 1, 36, 50, 8, 1, 49, 105, 35, 1, 1, 64, 196, 112, 10, 1, 81, 336, 294, 54, 1, 1, 100, 540, 672, 210, 12, 1, 121, 825, 1386, 660, 77, 1, 1, 144, 1210, 2640, 1782, 352, 14, 1, 169, 1716, 4719, 4290, 1287, 104, 1, 1
Offset: 1

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Author

Clark Kimberling, Feb 27 2012

Keywords

Comments

col 1: A000012
col 2: A000290 (squares)
col 3: A002415
col 4: A040977
col 5: A054334
row sums, u(n,1): A083329

Examples

			First five rows:
1
1...1
1...4
1...9....1
1...16...6
First five polynomials u(n,x):
1
1 + x
1 + 4x
1 + 9x + x^2
1 + 16x + 6x^2
		

Crossrefs

Cf. A208509.

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_] := 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[%]    (* A208508 *)
    Table[Expand[v[n, x]], {n, 1, z}]
    cv = Table[CoefficientList[v[n, x], x], {n, 1, z}];
    TableForm[cv]
    Flatten[%]    (* A208509 *)

Formula

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