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.

A207627 Triangle of coefficients of polynomials u(n,x) jointly generated with A207628; see the Formula section.

Original entry on oeis.org

1, 2, 3, 4, 4, 10, 8, 5, 18, 28, 16, 6, 28, 64, 72, 32, 7, 40, 120, 200, 176, 64, 8, 54, 200, 440, 576, 416, 128, 9, 70, 308, 840, 1456, 1568, 960, 256, 10, 88, 448, 1456, 3136, 4480, 4096, 2176, 512, 11, 108, 624, 2352, 6048, 10752, 13056, 10368, 4864
Offset: 1

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Author

Clark Kimberling, Feb 21 2012

Keywords

Comments

Column n is divisible by 2^(n-1); row n ends with 2^(n-1).

Examples

			First five rows:
1
2
3...4
4...10...8
5...18...28...16
		

Crossrefs

Cf. A207628.

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_] := 2 x*u[n - 1, x] + (x + 1)*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[%]    (* A207625 *)
    Table[Expand[v[n, x]], {n, 1, z}]
    cv = Table[CoefficientList[v[n, x], x], {n, 1, z}];
    TableForm[cv]
    Flatten[%]    (* A207626 *)

Formula

u(n,x)=u(n-1,x)+v(n-1,x),
v(n,x)=2x*u(n-1,x)+2x*v(n-1,x)+1,
where u(1,x)=1, v(1,x)=1.
The row sums =: 2, 7, 22, 67, ... are given by (5*3^n -1)/2 for n = 0, 1, 2, 3, ... . - Philippe Deléham, Feb 25 2012