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.

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A369336 Number of n X n Fishburn matrices with entries in the set {0,1,...,n}.

Original entry on oeis.org

1, 1, 12, 2052, 5684480, 305416893750, 391129148721673152, 14286237711414132094989064, 17309880507327972883933887341789184, 792117985317303404452447777723478865406570410, 1534214120588806182890487155420702132205591283310000000000
Offset: 0

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Author

Alois P. Heinz, Jan 20 2024

Keywords

Comments

Number of upper triangular n X n {0,1,...,n}-matrices with no zero rows or columns.

Examples

			a(0) = 1: [].
a(1) = 1: [1].
a(2) = 12:
  [10] [10] [20] [20]  [11] [11] [21] [21]  [12] [12] [22] [22]
  [ 1] [ 2] [ 1] [ 2]  [ 1] [ 2] [ 1] [ 2]  [ 1] [ 2] [ 1] [ 2].
		

Crossrefs

Main diagonal of A369415.

Programs

  • Maple
    a:= n-> coeff(series(add(x^j*mul(((n+1)^i-1)/(1+x*
        ((n+1)^i-1)), i=1..j), j=0..n), x, n+1), x, n):
    seq(a(n), n=0..10);

Formula

a(n) = [x^n] Sum_{j=0..n} x^j * Product_{i=1..j} ((n+1)^i-1)/(1+x*((n+1)^i-1)).

A369423 Number of 3 X 3 Fishburn matrices with entries in the set {0,1,...,n}.

Original entry on oeis.org

0, 10, 264, 2052, 9280, 30750, 83160, 194824, 410112, 794610, 1441000, 2475660, 4065984, 6428422, 9837240, 14634000, 21237760, 30155994, 41996232, 57478420, 77448000, 102889710, 134942104, 174912792, 224294400, 284781250, 358286760, 446961564, 553212352
Offset: 0

Views

Author

Alois P. Heinz, Jan 23 2024

Keywords

Comments

Number of upper triangular 3 X 3 {0,1,...,n}-matrices with no zero rows or columns.

Examples

			a(1) = 10:
  [100] [110] [100] [110] [101] [111] [101] [111] [110] [111]
  [ 10] [ 10] [ 11] [ 11] [ 10] [ 10] [ 11] [ 11] [ 01] [ 01]
  [  1] [  1] [  1] [  1] [  1] [  1] [  1] [  1] [  1] [  1].
		

Crossrefs

Row n=3 of A369415.

Programs

  • Maple
    a:= n-> n^3*(n+1)*(n^2+3*n+1):
    seq(a(n), n=0..28);
  • Mathematica
    Table[n^3*(n + 1)*(n^2 + 3*n + 1), {n, 0, 50}] (* Paolo Xausa, Jun 09 2024 *)

Formula

a(n) = n^3*(n+1)*(n^2+3*n+1) = n^6 + 4*n^5 + 4*n^4 + n^3.
G.f.: 2*x*(4*x^4-55*x^3-207*x^2-97*x-5)/(x-1)^7.
Showing 1-2 of 2 results.