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 1-8 of 8 results.

A347558 Number of minimum dominating sets in the n-ladder graph.

Original entry on oeis.org

2, 6, 3, 12, 2, 17, 2, 20, 2, 24, 2, 28, 2, 32, 2, 36, 2, 40, 2, 44, 2, 48, 2, 52, 2, 56, 2, 60, 2, 64, 2, 68, 2, 72, 2, 76, 2, 80, 2, 84, 2, 88, 2, 92, 2, 96, 2, 100, 2, 104, 2, 108, 2, 112, 2, 116, 2, 120, 2, 124, 2, 128, 2, 132, 2, 136, 2, 140, 2, 144, 2
Offset: 1

Views

Author

Eric W. Weisstein, Sep 06 2021

Keywords

Crossrefs

Row 2 of A350820.
Cf. A347634.

Programs

  • Mathematica
    Join[{2, 6, 3, 12, 2, 17}, LinearRecurrence[{0, 2, 0, -1}, {2, 20, 2, 24}, 20]]
    CoefficientList[Series[(2 + 6 x - x^2 - 2 x^4 - x^5 + x^6 - 2 x^7 + x^9)/((-1 + x)^2 (1 + x)^2), {x, 0, 20}], x]
  • PARI
    a(n)={if(n%2, 1, n+2)*2 + if(n<=6, [0,-2,1,0,0,1][n])} \\ Andrew Howroyd, Jan 18 2022

Formula

a(n) = 2*(n+2) for mod(n, 2)=0 and n != 2,6.
a(n) = 2 for mod(n, 2)=1 and n != 3.
a(n) = 2*a(n-2)-a(n-4) for n > 6.
G.f.: x*(2 + 6*x - x^2 - 2*x^4 - x^5 + x^6 - 2*x^7 + x^9)/((-1 + x)^2*(1 + x)^2).

A347633 Number of minimum dominating sets in the path graph P_n.

Original entry on oeis.org

1, 2, 1, 4, 3, 1, 8, 4, 1, 13, 5, 1, 19, 6, 1, 26, 7, 1, 34, 8, 1, 43, 9, 1, 53, 10, 1, 64, 11, 1, 76, 12, 1, 89, 13, 1, 103, 14, 1, 118, 15, 1, 134, 16, 1, 151, 17, 1, 169, 18, 1, 188, 19, 1, 208, 20, 1, 229, 21, 1, 251, 22, 1, 274, 23, 1, 298, 24, 1, 323
Offset: 1

Views

Author

Eric W. Weisstein, Sep 09 2021

Keywords

Crossrefs

Row 1 of A350815 and A350820.

Programs

  • Mathematica
    Table[Piecewise[{{1, Mod[n, 3] == 0}, {(n^2 + 13 n + 4)/18, Mod[n, 3] == 1}, {(n + 4)/3, Mod[n, 3] == 2}}], {n, 20}]
    LinearRecurrence[{0, 0, 3, 0, 0, -3, 0, 0, 1}, {1, 2, 1, 4, 3, 1, 8, 4, 1}, 20]
    CoefficientList[Series[-(1 + 2 x + x^2 + x^3 - 3 x^4 - 2 x^5 - x^6 + x^7 + x^8)/((-1 + x)^3 (1 + x + x^2)^3), {x, 0, 20}], x]
  • PARI
    a(n)={if(n%3==0, 1, if(n%3==1, (n^2+13*n+4)/18,  (n+4)/3))} \\ Andrew Howroyd, Jan 18 2022

Formula

a(n) = 1 for n = 0 (mod 3)
(n^2+13*n+4)/18 for n = 1 (mod 3)
(n+4)/3 for n = 2 (mod 3).
a(n) = 3*a(n-3)-3*a(n-6)+a(n-9) for n > 9.
G.f.: -(x*(1+2*x+x^2+x^3-3*x^4-2*x^5-x^6+x^7+x^8))/((-1+x)^3*(1+x+x^2)^3).

A350823 Array read by antidiagonals: T(m,n) is the 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, 2, 3, 3, 3, 2, 2, 3, 4, 4, 3, 2, 3, 4, 4, 4, 4, 4, 3, 3, 4, 5, 6, 6, 5, 4, 3, 3, 5, 6, 7, 7, 7, 6, 5, 3, 4, 5, 7, 7, 8, 8, 7, 7, 5, 4, 4, 6, 7, 8, 9, 10, 9, 8, 7, 6, 4, 4, 6, 8, 10, 11, 11, 11, 11, 10, 8, 6, 4
Offset: 1

Views

Author

Andrew Howroyd, Jan 17 2022

Keywords

Comments

Equivalently, the minimum number of X-pentominoes needed to cover an m X n grid.

Examples

			Table begins:
===================================
m\n | 1  2  3  4  5  6  7  8  9
----+------------------------------
  1 | 1  1  1  2  2  2  3  3  3 ...
  2 | 1  2  2  3  3  4  4  5  5 ...
  3 | 1  2  3  4  4  5  6  7  7 ...
  4 | 2  3  4  4  6  7  7  8 10 ...
  5 | 2  3  4  6  7  8  9 11 12 ...
  6 | 2  4  5  7  8 10 11 12 14 ...
  7 | 3  4  6  7  9 11 12 14 16 ...
  8 | 3  5  7  8 11 12 14 16 18 ...
  9 | 3  5  7 10 12 14 16 18 20 ...
  ...
		

Crossrefs

Row 4 is A193768.
Main diagonal is A104519.

Formula

T(m,n) = T(n,m).
T(1,n) = ceiling(n/3); T(2,n) = floor(n/2) + 1.

A347632 Number of minimum dominating sets in the n X n grid graph.

Original entry on oeis.org

1, 6, 10, 2, 22, 288, 2, 52, 32, 4, 32, 21600, 18, 540360, 34528, 100406, 70266144, 1380216154, 1682689266, 77900162, 233645826, 200997249200
Offset: 1

Views

Author

Eric W. Weisstein, Sep 09 2021

Keywords

Crossrefs

Main diagonal of A350820.
Cf. A104519 (domination number), A133515 (dominating sets), A290382 (minimal dominating sets).

Extensions

a(7)-a(12) from Andrew Howroyd, Jan 17 2022
a(13)-a(22) from Stephan Mertens, Aug 18 2024

A381474 Array read by antidiagonals: T(m,n) is the number of minimum connected dominating sets in the grid graph P_m X P_n.

Original entry on oeis.org

1, 2, 2, 1, 4, 1, 1, 1, 1, 1, 1, 7, 2, 7, 1, 1, 8, 1, 1, 8, 1, 1, 8, 1, 16, 1, 8, 1, 1, 8, 1, 62, 62, 1, 8, 1, 1, 8, 1, 10, 126, 10, 1, 8, 1, 1, 8, 1, 48, 11, 11, 48, 1, 8, 1, 1, 8, 1, 224, 448, 24, 448, 224, 1, 8, 1, 1, 8, 1, 8, 744, 13, 13, 744, 8, 1, 8, 1
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 ...
-----+------------------------------------------
   1 | 1 2 1   1    1  1    1     1  1     1 ...
   2 | 2 4 1   7    8  8    8     8  8     8 ...
   3 | 1 1 2   1    1  1    1     1  1     1 ...
   4 | 1 7 1  16   62 10   48   224  8    80 ...
   5 | 1 8 1  62  126 11  448   744  8  1898 ...
   6 | 1 8 1  10   11 24   13    14 15    16 ...
   7 | 1 8 1  48  448 13  800  6408  8  5240 ...
   8 | 1 8 1 224  744 14 6408 16288  8 82128 ...
   9 | 1 8 1   8    8 15    8     8 16     8 ...
  10 | 1 8 1  80 1898 16 5240 82128  8 87216 ...
  ...
		

Crossrefs

Main diagonal is A381730.

Formula

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

A375566 Array read by antidiagonals: T(m,n) = number of minimum dominating sets in the stacked prism graph C_m X P_n.

Original entry on oeis.org

1, 2, 2, 1, 6, 3, 4, 3, 9, 6, 3, 12, 34, 4, 5, 1, 2, 123, 4, 10, 3, 8, 17, 3, 16, 5, 51, 14, 4, 2, 18, 28, 290, 18, 14, 8, 1, 20, 93, 76, 320, 6, 63, 4, 3, 13, 2, 438, 164, 265, 171, 14, 4, 18, 25, 5, 24, 3, 396, 255, 36, 91, 24, 9, 120, 11, 1, 2, 27, 904, 250, 6, 1526, 60, 2052, 25, 22, 3
Offset: 1

Views

Author

Stephan Mertens, Aug 19 2024

Keywords

Examples

			Table starts:
====================================
m\n |   1   2   3    4    5    6 ...
----+-------------------------------
  1 |   1   2   1    4    3    1 ...
  2 |   2   6   3   12    2   17 ...
  3 |   3   9  34  123    3   18 ...
  4 |   6   4   4   16   28   76 ...
  5 |   5  10   5  290  320  265 ...
 ...
		

Crossrefs

Main diagonal is A375569.
Rows 1..2 are A347633, A347558.
Column 1 is A347538, column 2 is essentially A347634.

A350821 Number of minimum dominating sets in the grid graph P_3 X P_n.

Original entry on oeis.org

1, 3, 10, 29, 1, 2, 11, 46, 1, 3, 12, 60, 1, 4, 16, 78, 1, 5, 21, 103, 1, 6, 27, 134, 1, 7, 34, 172, 1, 8, 42, 218, 1, 9, 51, 273, 1, 10, 61, 338, 1, 11, 72, 414, 1, 12, 84, 502, 1, 13, 97, 603, 1, 14, 111, 718, 1, 15, 126, 848, 1, 16, 142, 994, 1, 17, 159, 1157, 1, 18
Offset: 1

Views

Author

Andrew Howroyd, Jan 17 2022

Keywords

Crossrefs

Row 3 of A350820.

Formula

a(n) = 4*a(n-4) - 6*a(n-8) + 4*a(n-12) - a(n-16) for n > 28.

A350822 Number of minimum dominating sets in the grid graph P_4 X P_n.

Original entry on oeis.org

4, 12, 29, 2, 52, 92, 2, 4, 324, 2, 10, 8, 2, 16, 32, 18, 22, 74, 90, 60, 134, 270, 258, 276, 612, 888, 852, 1298, 2382, 2886, 3278, 5590, 8538, 9902, 13444, 22100, 29864, 36526, 54578, 82602, 106156, 141074, 213858, 301224, 389912, 550584, 811542, 1098516, 1471482, 2126568
Offset: 1

Views

Author

Andrew Howroyd, Jan 17 2022

Keywords

Crossrefs

Row 4 of A350820.
Cf. A193768 (domination number).

Formula

a(n) = a(n-3) + 2*a(n-4) + a(n-7) for n > 16.
Showing 1-8 of 8 results.