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.

A209755 Triangle of coefficients of polynomials u(n,x) jointly generated with A209756; see the Formula section.

Original entry on oeis.org

1, 1, 2, 2, 4, 3, 3, 7, 8, 5, 4, 11, 17, 17, 8, 5, 16, 31, 41, 33, 13, 6, 22, 51, 83, 91, 63, 21, 7, 29, 78, 150, 205, 195, 117, 34, 8, 37, 113, 250, 406, 483, 403, 214, 55, 9, 46, 157, 392, 734, 1039, 1091, 812, 386, 89, 10, 56, 211, 586, 1239, 2023, 2536
Offset: 1

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Author

Clark Kimberling, Mar 14 2012

Keywords

Comments

Column 1: 1,2,3,4,5,6,....... A000027
Column 2: 1,2,4,7,11,........ A000124
Column 3: 2,6,13,24,......... A105163
Final row terms: 1,2,3,5,.... A000045 (Fibonacci numbers)
Row sums: 1,3,9,23,57,139,... A133654
Alternating row sums: 1,-1,1,-1,1,-1,1,-1,...; A033999
For a discussion and guide to related arrays, see A208510.

Examples

			First five rows:
1
1...2
2...4....3
3...7....8....5
4...11...11...17...8
First three polynomials u(n,x): 1, 1 + 2x, 2 + 4x + 3x^2.
		

Crossrefs

Programs

  • Mathematica
    u[1, x_] := 1; v[1, x_] := 1; z = 16;
    u[n_, x_] := x*u[n - 1, x] + (x + 1)*v[n - 1, x];
    v[n_, x_] := 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[%]    (* A209755 *)
    Table[Expand[v[n, x]], {n, 1, z}]
    cv = Table[CoefficientList[v[n, x], x], {n, 1, z}];
    TableForm[cv]
    Flatten[%]    (* A209756 *)
    Table[u[n, x] /. x -> 1, {n, 1, z}]   (* A133654 *)
    Table[v[n, x] /. x -> 1, {n, 1, z}]   (* A001333 *)
    Table[u[n, x] /. x -> -1, {n, 1, z}]  (* A033999 *)
    Table[v[n, x] /. x -> -1, {n, 1, z}]  (* A109613 *)

Formula

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