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 1-4 of 4 results.

A292074 Number of minimum dominating sets in the n X n rook complement graph.

Original entry on oeis.org

1, 4, 48, 240, 1000, 3300, 9114, 21952, 47520, 94500, 175450, 307824, 515112, 828100, 1286250, 1939200, 2848384, 4088772, 5750730, 7942000, 10789800, 14443044, 19074682, 24884160, 32100000, 40982500, 51826554, 64964592, 80769640, 99658500, 122095050
Offset: 1

Views

Author

Eric W. Weisstein, Sep 12 2017

Keywords

Comments

The minimum dominating sets are the minimal dominating sets (A291623) of size equal to the domination number. For n > 2, the domination number is 3. For n > 3, the minimal dominating sets of size 3 are either any three vertices such that no two are in the same row or column or any vertex with another in the same row and a third in the same column. For n = 3, the case of all vertices in a single row or column also needs to be included. - Andrew Howroyd, Sep 13 2017

Crossrefs

Programs

  • Mathematica
    Join[{1, 4, 48}, LinearRecurrence[{7, -21, 35, -35, 21, -7, 1}, {240, 1000, 3300, 9114, 21952, 47520, 94500}, 20]]
    Table[Piecewise[{{1, n == 1}, {48, n == 3}}, 6 Binomial[n, 3]^2 + n^2 (n - 1)^2], {n, 20}]
    CoefficientList[Series[(-1 + 3 x - 41 x^2 + 47 x^3 - 223 x^4 + 221 x^5 - 217 x^6 + 127 x^7 - 42 x^8 + 6 x^9)/(-1 + x)^7, {x, 0, 20}], x]
  • PARI
    a(n) = if(n<4, [1,4,48][n], 6*binomial(n, 3)^2 + n^2*(n-1)^2); \\ Andrew Howroyd, Sep 13 2017

Formula

G.f.: x*(-1 + 3*x - 41*x^2 + 47*x^3 - 223*x^4 + 221*x^5 - 217*x^6 + 127*x^7 - 42*x^8 + 6*x^9)/(-1 + x)^7.
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 > 10.
a(n) = 6*binomial(n, 3)^2 + n^2*(n-1)^2 for n > 3. - Andrew Howroyd, Sep 13 2017

Extensions

Terms a(6) and beyond from Andrew Howroyd, Sep 13 2017

A384121 Array read by antidiagonals: T(n,m) is the number of 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, 9, 1, 1, 1, 1, 39, 39, 1, 1, 1, 1, 183, 421, 183, 1, 1, 1, 1, 833, 3825, 3825, 833, 1, 1, 1, 1, 3629, 32047, 64727, 32047, 3629, 1, 1, 1, 1, 15291, 260355, 1046425, 1046425, 260355, 15291, 1, 1, 1, 1, 63051, 2092909, 16771879, 33548731, 16771879, 2092909, 63051, 1, 1
Offset: 0

Views

Author

Andrew Howroyd, May 20 2025

Keywords

Comments

Non-dominating sets are just those that are contained in the union of a single row and column minus the intersecting vertex.

Examples

			Array begins:
===============================================================
n\m | 0 1     2       3         4           5             6 ...
----+----------------------------------------------------------
  0 | 1 1     1       1         1           1             1 ...
  1 | 1 1     1       1         1           1             1 ...
  2 | 1 1     9      39       183         833          3629 ...
  3 | 1 1    39     421      3825       32047        260355 ...
  4 | 1 1   183    3825     64727     1046425      16771879 ...
  5 | 1 1   833   32047   1046425    33548731    1073727713 ...
  6 | 1 1  3629  260355  16771879  1073727713   68719441881 ...
  7 | 1 1 15291 2092909 268422785 34359704907 4398046428559 ...
  ...
		

Crossrefs

Main diagonal is A292073.
Columns 0 and 1 are A000012.
Column 2 is A287063, n > 1.
Cf. A384120 (independent sets), A384122, A384123.

Programs

  • PARI
    T(n,m) = if(n<=1 || m<=1, 1, 2^(n*m) - n*(2^m-2) - m*(2^n-2) + n*m - n*m*(2^(m-1)-1)*(2^(n-1)-1) + n*(n-1)*m*(m-1)/2 - 1)

Formula

T(n,m) = 2^(n*m) - n*(2^m-2) - m*(2^n-2) + n*m - n*m*(2^(m-1)-1)*(2^(n-1)-1) + n*(n-1)*m*(m-1)/2 - 1 for n > 1, m > 1.
T(n,m) = T(m,n).

A303209 Number of total dominating sets in the n X n rook complement graph.

Original entry on oeis.org

0, 1, 334, 63935, 33543096, 68719407273, 562949953031502, 18446744073707484655, 2417851639229258338871776, 1267650600228229401496650964865, 2658455991569831745807614120307390270, 22300745198530623141535718272648360299110799
Offset: 1

Views

Author

Eric W. Weisstein, Apr 19 2018

Keywords

Comments

The vertex sets which are not totally dominating are just those that are contained in the union of a single row and column. - Andrew Howroyd, Apr 20 2018

Crossrefs

Programs

  • PARI
    a(n) = {2^(n^2) - 2*n*(2^n - 1) - 2*n^2*(2^(n-1)-1)^2 + n^2*(n-1)^2/2 + n^2 - 1} \\ Andrew Howroyd, Apr 20 2018

Formula

a(n) = 2^(n^2) - 2*n*(2^n - 1) - 2*n^2*(2^(n-1)-1)^2 + n^2*(n-1)^2/2 + n^2 - 1. - Andrew Howroyd, Apr 20 2018

Extensions

Terms a(6) and beyond from Andrew Howroyd, Apr 20 2018

A290949 Number of connected dominating sets in the n X n rook complement graph.

Original entry on oeis.org

1, 0, 325, 63899, 33542996, 68719407048, 562949953031061, 18446744073707483871, 2417851639229258338870480, 1267650600228229401496650962840, 2658455991569831745807614120307387245, 22300745198530623141535718272648360299106443
Offset: 1

Views

Author

Eric W. Weisstein, Sep 14 2017

Keywords

Crossrefs

Programs

  • Mathematica
    Table[If[n == 1, 1, 2^(n^2) - 2 n (2^n - 1) + n^2 (1 - 2 (2^(n - 1) - 1)^2 + (n - 1)^2) - 3 Binomial[n, 2]^2 - 1], {n, 20}] (* Eric W. Weisstein, Jan 15 2018 *)
  • PARI
    a(n) = if(n==1, 1, 2^(n^2) - 2*n*(2^n - 1) + n^2 - 2*n^2*(2^(n-1)-1)^2 + n^2*(n-1)^2 - 3*binomial(n,2)^2 - 1); \\ Andrew Howroyd, Jan 14 2018

Formula

a(n) = 2^(n^2) - 2*n*(2^n - 1) + n^2 - 2*n^2*(2^(n-1)-1)^2 + n^2*(n-1)^2 - 3*binomial(n,2)^2 - 1 for n > 1. - Andrew Howroyd, Jan 14 2018

Extensions

a(6)-a(12) from Andrew Howroyd, Jan 14 2018
Showing 1-4 of 4 results.