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.

A303208 Number of total dominating sets in the n X n rook graph.

Original entry on oeis.org

0, 9, 334, 53731, 30844786, 66544564805, 556588617042914, 18376877842518517955, 2414913046805958120844234, 1267171440764716263069641387581, 2658150749788131925244338204731596650, 22299981643440069703358952237798936248817875
Offset: 1

Views

Author

Eric W. Weisstein, Apr 19 2018

Keywords

Crossrefs

Main diagonal of A384116.

Programs

  • Mathematica
    b[0] = 1; b[n_] := (2^n - 1)^n + Sum[Binomial[n, i] Sum[(-1)^j (-1 + 2^(n - j))^i Binomial[n, j], {j, 0, n}], {i, n - 1}]; Table[Sum[(-1)^k Binomial[n, k]^2 k! b[n - k], {k, 0, n}], {n, 10}]
  • PARI
    \\ here c(n) is A287065.
    b(m, n)=sum(j=0, m, (-1)^j*binomial(m, j)*(2^(m - j) - 1)^n);
    c(n)=(2^n-1)^n + sum(i=1, n-1, b(n, i)*binomial(n, i));
    a(n) = {sum(k=0, n, (-1)^k*binomial(n,k)^2*k!*c(n-k))} \\ Andrew Howroyd, Apr 20 2018

Formula

a(n) = Sum_{k=0..n} (-1)^k*binomial(n,k)^2*k!*A287065(n-k). - Andrew Howroyd, Apr 20 2018
a(n) ~ 2^(n^2). - Vaclav Kotesovec, Apr 20 2018

Extensions

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

A384117 Array read by antidiagonals: T(n,m) is the number of minimum 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, 3, 3, 6, 1, 1, 10, 4, 6, 4, 10, 1, 1, 15, 5, 4, 4, 5, 15, 1, 1, 21, 6, 5, 80, 5, 6, 21, 1, 1, 28, 7, 6, 65, 65, 6, 7, 28, 1, 1, 36, 8, 7, 96, 410, 96, 7, 8, 36, 1, 1, 45, 9, 8, 133, 306, 306, 133, 8, 9, 45, 1
Offset: 0

Views

Author

Andrew Howroyd, May 19 2025

Keywords

Comments

For 1 < m <= n, the minimum size of a total dominating set is m. When 1 < m < n, solutions have exactly one vertex in each column. In the special case of n = m, solutions either have exactly one vertex in each column or have exactly one vertex in each row.

Examples

			Array begins:
============================================
n\m | 0  1 2 3   4   5    6     7      8 ...
----+---------------------------------------
  0 | 1  1 1 1   1   1    1     1      1 ...
  1 | 1  0 1 3   6  10   15    21     28 ...
  2 | 1  1 4 3   4   5    6     7      8 ...
  3 | 1  3 3 6   4   5    6     7      8 ...
  4 | 1  6 4 4  80  65   96   133    176 ...
  5 | 1 10 5 5  65 410  306   427    568 ...
  6 | 1 15 6 6  96 306 5112  4207   6448 ...
  7 | 1 21 7 7 133 427 4207 48818  38424 ...
  8 | 1 28 8 8 176 568 6448 38424 695424 ...
  ...
		

Crossrefs

Main diagonal is A303211.
Column 0 is A000012.
Column 1 is A000217(n-1), n > 0.

Programs

  • PARI
    B(n,k) = {if(k<=n, if(k==1, binomial(n,2), sum(i=0, k, (-1)^i * binomial(k,i) * binomial(n,i) * i! * (n-i)^(k-i))))}
    T(n,m) = {if(n==0&&m==0, 1, B(n,m) + B(m,n))}

Formula

T(n,m) = Sum_{i=0..m} (-1)^i * binomial(m,i) * binomial(n,i) * i! * (n-i)^(m-i) for 1 < m < n.
T(n,m) = T(m,n).
T(n,2) = T(n,3) = n for n >= 4.

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.