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 1-3 of 3 results.

A292073 Number of dominating sets in the n X n rook complement graph.

Original entry on oeis.org

1, 9, 421, 64727, 33548731, 68719441881, 562949953225997, 18446744073708516927, 2417851639229258344138819, 1267650600228229401496677076985, 2658455991569831745807614120434020301, 22300745198530623141535718272648360902500919
Offset: 1

Views

Author

Eric W. Weisstein, Sep 12 2017

Keywords

Comments

Non-dominating sets are just those that are contained in the union of a single row and column minus the intersecting vertex. - Andrew Howroyd, Sep 13 2017

Crossrefs

Programs

  • Magma
    [1] cat [2^(n^2)-2*n*(2^n-2)+n^2-n^2*(2^(n-1)-1)^2+ n^2*(n-1)^2-2*Binomial(n,2)^2-1: n in [2..15]]; // Vincenzo Librandi, Mar 17 2018
  • Mathematica
    Table[If[n == 1, 1, 2^n^2 + (2^n (n - 2) - 4^(n - 1) n + (n - 1)^2 n/2 + 4) n - 1], {n, 20}]
  • PARI
    a(n) = if(n == 1, 1, 2^(n^2) - 2*n*(2^n - 2) + n^2 - n^2*(2^(n-1)-1)^2 + n^2*(n-1)^2 - 2*binomial(n,2)^2 - 1); \\ Andrew Howroyd, Sep 13 2017
    

Formula

a(n) = 2^(n^2) - 2*n*(2^n - 2) + n^2 - n^2*(2^(n-1)-1)^2 + n^2*(n-1)^2 - 2*binomial(n,2)^2 - 1 for n > 1. - Andrew Howroyd, Sep 13 2017

Extensions

a(6)-a(12) from Andrew Howroyd, Sep 13 2017

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

A384122 Array read by antidiagonals: T(n,m) is the number of minimum dominating sets in the n X m rook complement graph.

Original entry on oeis.org

1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 1, 4, 1, 1, 1, 1, 3, 3, 1, 1, 1, 1, 4, 48, 4, 1, 1, 1, 1, 5, 100, 100, 5, 1, 1, 1, 1, 6, 185, 240, 185, 6, 1, 1, 1, 1, 7, 306, 480, 480, 306, 7, 1, 1, 1, 1, 8, 469, 840, 1000, 840, 469, 8, 1, 1, 1, 1, 9, 680, 1344, 1800, 1800, 1344, 680, 9, 1, 1
Offset: 0

Views

Author

Andrew Howroyd, May 20 2025

Keywords

Comments

For n >= 3, m >= 3, the minimum size of a dominating set is 3.

Examples

			Array begins:
===============================================
n\m | 0 1 2   3    4    5    6     7     8 ...
----+------------------------------------------
  0 | 1 1 1   1    1    1    1     1     1 ...
  1 | 1 1 1   1    1    1    1     1     1 ...
  2 | 1 1 4   3    4    5    6     7     8 ...
  3 | 1 1 3  48  100  185  306   469   680 ...
  4 | 1 1 4 100  240  480  840  1344  2016 ...
  5 | 1 1 5 185  480 1000 1800  2940  4480 ...
  6 | 1 1 6 306  840 1800 3300  5460  8400 ...
  7 | 1 1 7 469 1344 2940 5460  9114 14112 ...
  8 | 1 1 8 680 2016 4480 8400 14112 21952 ...
   ...
		

Crossrefs

Main diagonal is A292074.
Column 3 is A090197(n-1), n >= 4.
Column 4 is A272871(n), n >= 4.

Programs

  • PARI
    T(n,m) = if(n<=2||m<=2, if(n<=1||m<=1, 1, if(n==2,m)+if(m==2,n)), 4*binomial(n,2)*binomial(m,2) + 6*binomial(n,3)*binomial(m,3) + if(n==3,m) + if(m==3,n))

Formula

T(n,m) = 4*binomial(n,2)*binomial(m,2) + 6*binomial(n,3)*binomial(m,3) for n >= 4, m >= 4.
T(n,m) = T(m,n).
T(n,0) = T(n,1) = 1.
Showing 1-3 of 3 results.