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.

Showing 1-2 of 2 results.

A303212 Number of minimum total dominating sets in the n X n rook complement graph.

Original entry on oeis.org

0, 1, 6, 96, 600, 2400, 7350, 18816, 42336, 86400, 163350, 290400, 490776, 794976, 1242150, 1881600, 2774400, 3995136, 5633766, 7797600, 10613400, 14229600, 18818646, 24579456, 31740000, 40560000, 51333750, 64393056, 80110296, 98901600
Offset: 1

Views

Author

Eric W. Weisstein, Apr 19 2018

Keywords

Comments

For n > 2, the minimum total dominating sets are any three vertices such that no two are in the same row or column. - Andrew Howroyd, Apr 20 2018
Essentially the same as A179058(n), differing only for n=2. - Eric W. Weisstein, Dec 06 2023

Crossrefs

Programs

  • Mathematica
    Table[If[n == 2, 1, 6 Binomial[n, 3]^2], {n, 20}]
    Join[{0, 1}, LinearRecurrence[{7, -21, 35, -35, 21, -7, 1}, {0, 0, 6, 96, 600, 2400, 7350}, {3, 20}]]
    CoefficientList[Series[x (-1 + x - 75 x^2 - 19 x^3 - 41 x^4 + 21 x^5 - 7 x^6 + x^7)/(-1 + x)^7, {x, 0, 20}], x]
  • PARI
    a(n) = if(n<3, n==2, 6*binomial(n,3)^2) \\ Andrew Howroyd, Apr 20 2018
    
  • PARI
    concat(0, Vec(x^2*(1 - x + 75*x^2 + 19*x^3 + 41*x^4 - 21*x^5 + 7*x^6 - x^7) / (1 - x)^7 + O(x^60))) \\ Colin Barker, Apr 20 2018

Formula

a(n) = A179058(n) for n > 2. - Andrew Howroyd, Apr 20 2018
From Colin Barker, Apr 20 2018: (Start)
G.f.: x^2*(1 - x + 75*x^2 + 19*x^3 + 41*x^4 - 21*x^5 + 7*x^6 - x^7) / (1 - x)^7.
a(n) = n^2*(2 - 3*n + n^2)^2 / 6 for n > 2.
a(n) = 7*a(n-1) - 21*a(n-2) + 35*a(n-3) - 35*a(n-4) + 21*a(n-5) - 7*a(n-6) + a(n-7) for n > 9.
(End)

Extensions

a(6)-a(30) from Andrew Howroyd, Apr 20 2018

A347922 Number of minimal total dominating sets in the n X n rook complement graph.

Original entry on oeis.org

0, 1, 51, 492, 2500, 8925, 25431, 61936, 134352, 266625, 493075, 861036, 1433796, 2293837, 3546375, 5323200, 7786816, 11134881, 15604947, 21479500, 29091300, 38829021, 51143191, 66552432, 85650000, 109110625, 137697651, 172270476, 213792292, 263338125
Offset: 1

Views

Author

Eric W. Weisstein, Sep 19 2021

Keywords

Comments

From Andrew Howroyd, Jan 19 2022: (Start)
The vertex sets which are not totally dominating are just those that are contained in the union of a single row and column. Minimal total dominating sets are:
- any three vertices such that no two are in the same row or column,
- two vertices in each of two rows/columns. (End)

Crossrefs

Programs

  • Mathematica
    Table[(n - 1)^2 n^2 (5 n^2 - 11 n + 5)/12, {n, 20}] (* Eric W. Weisstein, May 11 2024 *)
    LinearRecurrence[{7, -21, 35, -35, 21, -7, 1}, {0, 1, 51, 492, 2500, 8925, 25431}, 20] (* Eric W. Weisstein, May 11 2024 *)
    CoefficientList[Series[-x (1 + 44 x + 156 x^2 + 92 x^3 + 7 x^4)/(-1 + x)^7, {x, 0, 20}], x] (* Eric W. Weisstein, May 11 2024 *)
  • PARI
    a(n) = (5*n^2 - 11*n + 5)*n^2*(n-1)^2/12 \\ Andrew Howroyd, Jan 19 2022

Formula

From Andrew Howroyd, Jan 19 2022: (Start)
a(n) = 6*binomial(n,3)^2 + 2*binomial(n,2)^3 - binomial(n,2)^2.
a(n) = (5*n^2 - 11*n + 5)*n^2*(n-1)^2/12.
G.f.: x*(1 + 44*x + 156*x^2 + 92*x^3 + 7*x^4)/(1 - x)^7.
(End)

Extensions

Terms a(6) and beyond from Andrew Howroyd, Jan 19 2022
Showing 1-2 of 2 results.