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.

A384116 Array read by antidiagonals: T(n,m) is the number of total dominating sets in the n X m rook graph K_n X K_m.

Original entry on oeis.org

1, 1, 1, 1, 0, 1, 1, 1, 1, 1, 1, 4, 9, 4, 1, 1, 11, 39, 39, 11, 1, 1, 26, 183, 334, 183, 26, 1, 1, 57, 833, 3087, 3087, 833, 57, 1, 1, 120, 3629, 27472, 53731, 27472, 3629, 120, 1, 1, 247, 15291, 236127, 922515, 922515, 236127, 15291, 247, 1, 1, 502, 63051, 1975246, 15524639, 30844786, 15524639, 1975246, 63051, 502, 1
Offset: 0

Views

Author

Andrew Howroyd, May 19 2025

Keywords

Examples

			Array begins:
=================================================================
n\m | 0   1     2       3         4           5             6 ...
----+------------------------------------------------------------
  0 | 1   1     1       1         1           1             1 ...
  1 | 1   0     1       4        11          26            57 ...
  2 | 1   1     9      39       183         833          3629 ...
  3 | 1   4    39     334      3087       27472        236127 ...
  4 | 1  11   183    3087     53731      922515      15524639 ...
  5 | 1  26   833   27472    922515    30844786    1019569593 ...
  6 | 1  57  3629  236127  15524639  1019569593   66544564805 ...
  7 | 1 120 15291 1975246 256594143 33329148492 4314985562475 ...
  ...
		

Crossrefs

Main diagonal is A303208.
Column 0 is A000012.
Column 1 is A000295(n), n > 0.
Column 2 is A287063(n), n > 1.

Programs

  • PARI
    B(n,m) = {sum(i=0, min(n,m), (-1)^i*binomial(n,i)*binomial(m,i)*i!*(2^(n-i)-1)^(m-i))}
    T(n,m) = {B(n,m) - sum(i=1, m, (-1)^i*binomial(m,i)*B(m-i,n))}

Formula

T(n,m) = B(n,m) - Sum_{i=1..m} (-1)^i*binomial(m,i)*B(m-i,n), where B(n,m) = Sum_{i=0..m} (-1)^i*binomial(n,i)*binomial(m,i)*i!*(2^(n-i)-1)^(m-i).
T(n,m) = T(m,n).

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).

A294140 Number of total dominating sets in the n-crown graph.

Original entry on oeis.org

0, 1, 16, 121, 676, 3249, 14400, 61009, 252004, 1026169, 4145296, 16670889, 66879684, 267944161, 1072693504, 4292739361, 17175150916, 68709515625, 274856935824, 1099467588025, 4397954236900, 17591993106961, 70368341525056, 281474137850481, 1125898162012836
Offset: 1

Views

Author

Eric W. Weisstein, Apr 16 2018

Keywords

Comments

In a total dominating set each side of the crown graph requires any two vertices on the other side to dominate it. - Andrew Howroyd, Apr 16 2018

Crossrefs

Programs

  • Mathematica
    Table[(1 - 2^n + n)^2, {n, 20}]
    LinearRecurrence[{11, -47, 101, -116, 68, -16}, {0, 1, 16, 121, 676, 3249}, 20]
    CoefficientList[Series[x (1 + 5 x - 8 x^2 - 4 x^3)/((-1 + x)^3 (-1 + 2 x)^2 (-1 + 4 x)), {x, 0, 20}], x]
  • PARI
    a(n)=(2^n-1-n)^2; \\ Andrew Howroyd, Apr 16 2018

Formula

a(n) = (2^n - 1 - n)^2. - Andrew Howroyd, Apr 16 2018
a(n) = 11*a(n-1) - 47*a(n-2) + 101*a(n-3) - 116*a(n-4) + 68*a(n-5) -16*a(n-6).
G.f.: x^2*(1 + 5*x - 8*x^2 - 4*x^3)/((-1 + x)^3*(-1 + 2*x)^2*(-1 + 4*x)).

Extensions

a(1)-a(2) and a(11)-a(25) from Andrew Howroyd, Apr 16 2018
Showing 1-3 of 3 results.