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.

A350820 Array read by antidiagonals: T(m,n) is the number of minimum dominating sets in the grid graph P_m X P_n.

Original entry on oeis.org

1, 2, 2, 1, 6, 1, 4, 3, 3, 4, 3, 12, 10, 12, 3, 1, 2, 29, 29, 2, 1, 8, 17, 1, 2, 1, 17, 8, 4, 2, 2, 52, 52, 2, 2, 4, 1, 20, 11, 92, 22, 92, 11, 20, 1, 13, 2, 46, 2, 13, 13, 2, 46, 2, 13, 5, 24, 1, 4, 3, 288, 3, 4, 1, 24, 5, 1, 2, 3, 324, 344, 34, 34, 344, 324, 3, 2, 1
Offset: 1

Views

Author

Andrew Howroyd, Jan 17 2022

Keywords

Comments

The domination number of the grid graphs is tabulated in A350823.

Examples

			Table begins:
===================================
m\n | 1  2  3  4   5   6  7   8
----+------------------------------
  1 | 1  2  1  4   3   1  8   4 ...
  2 | 2  6  3 12   2  17  2  20 ...
  3 | 1  3 10 29   1   2 11  46 ...
  4 | 4 12 29  2  52  92  2   4 ...
  5 | 3  2  1 52  22  13  3 344 ...
  6 | 1 17  2 92  13 288 34   2 ...
  7 | 8  2 11  2   3  34  2  34 ...
  8 | 4 20 46  4 344   2 34  52 ...
  ...
		

Crossrefs

Rows 1..4 are A347633, A347558, A350821, A350822.
Main diagonal is A347632.
Cf. A218354 (dominating sets), A286847 (minimal dominating sets), A303293, A350815, A350823.

Formula

T(m,n) = T(n,m).

A193768 The domination number of the 4 X n board.

Original entry on oeis.org

2, 3, 4, 4, 6, 7, 7, 8, 10, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63, 64, 65, 66, 67
Offset: 1

Views

Author

Andrew Buchanan, Tanya Khovanova, Alex Ryba, Aug 06 2011

Keywords

Comments

The domination number of a rectangular grid is the minimal number of X-pentominoes or its fragments that can cover the board.

Examples

			You can't cover the 1 by 4 board with an X-pentomino, but you can do it with two of them.
		

Crossrefs

Programs

  • Mathematica
    LinearRecurrence[{2,-1},{2,3,4,4,6,7,7,8,10,10,11},70] (* Harvey P. Dale, Feb 17 2020 *)
  • PARI
    Vec(x*(x^10-2*x^9+x^8+x^7-x^6-x^5+2*x^4-x^3-x+2)/(x-1)^2 + O(x^100)) \\ Colin Barker, Oct 05 2014

Formula

a(n) = n, except for n = 1, 2, 3, 5, 6 or 9. For the exceptions a(n) = n+1.
a(n) = 4n - A193767(n).
a(n) = 2*a(n-1)-a(n-2) for n>11. - Colin Barker, Oct 05 2014
G.f.: x*(x^10-2*x^9+x^8+x^7-x^6-x^5+2*x^4-x^3-x+2) / (x-1)^2. - Colin Barker, Oct 05 2014

A375603 Array read by antidiagonals: T(m,n) = domination number of the stacked prism graph C_m X P_n.

Original entry on oeis.org

1, 1, 1, 1, 2, 1, 2, 2, 2, 2, 2, 3, 3, 2, 2, 2, 3, 4, 3, 3, 2, 3, 4, 4, 4, 4, 4, 3, 3, 4, 5, 5, 6, 5, 4, 3, 3, 5, 6, 6, 7, 6, 6, 4, 3, 4, 5, 7, 7, 8, 8, 7, 6, 5, 4, 4, 6, 7, 8, 9, 9, 9, 8, 7, 6, 4, 4, 6, 8, 9, 10, 10, 11, 10, 10, 8, 6, 4, 5, 7, 9, 10, 11, 12, 12, 12, 12, 10, 9, 6, 5
Offset: 1

Views

Author

Stephan Mertens, Aug 20 2024

Keywords

Examples

			Table starts:
====================================
m\n |   1   2   3    4    5    6 ...
----|-------------------------------
  1 |   1   1   1    2    2    2 ...
  2 |   1   2   2    3    3    4 ...
  3 |   1   2   3    4    4    5 ...
  4 |   2   2   3    4    5    6 ...
  5 |   2   3   4    6    7    8 ...
  6 |   2   4   5    6    8    9 ...
 ...
		

Crossrefs

Main diagonal is A375601.

A381475 Array read by antidiagonals: T(m,n) is the connected domination number of the grid graph P_m X P_n.

Original entry on oeis.org

1, 1, 1, 1, 2, 1, 2, 2, 2, 2, 3, 4, 3, 4, 3, 4, 5, 4, 4, 5, 4, 5, 6, 5, 7, 5, 6, 5, 6, 7, 6, 9, 9, 6, 7, 6, 7, 8, 7, 10, 11, 10, 7, 8, 7, 8, 9, 8, 12, 12, 12, 12, 8, 9, 8, 9, 10, 9, 14, 15, 14, 15, 14, 9, 10, 9, 10, 11, 10, 15, 17, 16, 16, 17, 15, 10, 11, 10
Offset: 1

Views

Author

Andrew Howroyd, Mar 19 2025

Keywords

Examples

			Table begins:
=========================================================
m\n |  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 ...
----+----------------------------------------------------
  1 |  1  1  1  2  3  4  5  6  7  8  9 10 11 12 13 14 ...
  2 |  1  2  2  4  5  6  7  8  9 10 11 12 13 14 15 16 ...
  3 |  1  2  3  4  5  6  7  8  9 10 11 12 13 14 15 16 ...
  4 |  2  4  4  7  9 10 12 14 15 17 19 20 22 24 25 27 ...
  5 |  3  5  5  9 11 12 15 17 18 21 23 24 27 29 30 33 ...
  6 |  4  6  6 10 12 14 16 18 20 22 24 26 28 30 32 34 ...
  7 |  5  7  7 12 15 16 20 23 24 28 31 32 36 39 40 44 ...
  8 |  6  8  8 14 17 18 23 26 27 32 35 36 41 44 45 50 ...
  9 |  7  9  9 15 18 20 24 27 30 33 36 39 42 45 48 51 ...
  ...
		

Crossrefs

Main diagonal is A369692.

Formula

T(m,n) = T(n,m).
Showing 1-4 of 4 results.