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.

A303211 Number of minimum total dominating sets in the n X n rook graph.

Original entry on oeis.org

0, 4, 6, 80, 410, 5112, 48818, 695424, 9589266, 162327800, 2869193162, 57451559904, 1225220612954, 28560612445848, 709917843398850, 18943086191785472, 536695850359985186, 16151064034012994808, 513345798896635886906, 17206881800061632191200
Offset: 1

Views

Author

Eric W. Weisstein, Apr 19 2018

Keywords

Crossrefs

Main diagonal of A384117.

Programs

  • Mathematica
    Table[(-1)^n n! + Sum[(-1)^k Binomial[n, k]^2 k! (2 (n - k)^(n - k) - (n - k)!), {k, 0, n - 1}], {n, 20}]
    2 Table[(-1)^n n! + Sum[(-1)^k Binomial[n, k]^2 k! (n - k)^(n - k), {k, 0, n - 1}], {n, 20}] (* Eric W. Weisstein, Jan 18 2019 *)
  • PARI
    a(n) = {sum(k=0, n, (-1)^k*binomial(n,k)^2*k!*(2*(n-k)^(n-k) - (n-k)!))} \\ Andrew Howroyd, Apr 20 2018

Formula

a(n) = Sum_{k=0,..n} (-1)^k*binomial(n,k)^2*k!*(2*(n-k)^(n-k) - (n-k)!). - Andrew Howroyd, Apr 20 2018
a(n) ~ 2 * (exp(1) - 1)^(n + 1/2) * n^n / exp(n + 1/2). - Vaclav Kotesovec, Apr 20 2018

Extensions

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

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).

A384118 Array read by antidiagonals: T(n,m) is the number of minimal 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, 3, 4, 3, 1, 1, 6, 5, 5, 6, 1, 1, 10, 12, 51, 12, 10, 1, 1, 15, 37, 97, 97, 37, 15, 1, 1, 21, 98, 218, 368, 218, 98, 21, 1, 1, 28, 219, 519, 2229, 2229, 519, 219, 28, 1, 1, 36, 430, 1417, 6232, 7310, 6232, 1417, 430, 36, 1
Offset: 0

Views

Author

Andrew Howroyd, May 19 2025

Keywords

Examples

			Array begins:
=====================================================
n\m | 0  1   2    3     4      5       6        7 ...
----+------------------------------------------------
  0 | 1  1   1    1     1      1       1        1 ...
  1 | 1  0   1    3     6     10      15       21 ...
  2 | 1  1   4    5    12     37      98      219 ...
  3 | 1  3   5   51    97    218     519     1417 ...
  4 | 1  6  12   97   368   2229    6232    16013 ...
  5 | 1 10  37  218  2229   7310   44491   172387 ...
  6 | 1 15  98  519  6232  44491  301572  1345693 ...
  7 | 1 21 219 1417 16013 172387 1345693 10893008 ...
  ...
		

Crossrefs

Main diagonal is A347921.

Programs

  • PARI
    B(n,m)={ my(M=matrix(n+1,m+1)); for(n=1, n, M[n+1,1]=1; for(m=1, m, M[n+1,m+1] = if(n>2, binomial(n,2)*M[n-1,m]) + sum(i=2, m, binomial(m-1,i-1)*(n*M[n, m-i+1] + if(i>=3&&i<=n, binomial(n,i-1)*i!*M[n-i+2,m-i+1] ) )))); M}
    A(n,m)={ my(M=B(m,n) + B(n,m)~); M[1,1]=1; for(i=1, m, for(j=1, n, if((i+j)%3==0 && j<=2*i && i<=2*j, my(t=(i+j)/3); M[i+1,j+1] += binomial(i,j-t)*binomial(j,i-t)*(2*(j-t))!*(2*(i-t))!/2^t ))); M}
    { my(T=A(8,8)); for(i=1, #T, print(T[i, ])) }

Formula

T(n,m) = T(m,n).
Showing 1-3 of 3 results.