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 1-2 of 2 results.

A248744 Number of different ways one can attack all squares on an n X n chessboard with n rooks.

Original entry on oeis.org

1, 1, 6, 48, 488, 6130, 92592, 1642046, 33514112, 774478098, 19996371200, 570583424422, 17831721894912, 605743986163706, 22223926472824832, 875786473087350750, 36893467224629215232, 1654480168085245432354, 78692809748219369422848, 3956839189675526769415958
Offset: 0

Views

Author

Stephen Penrice, Apr 09 2017

Keywords

Comments

Number of minimum (and minimal) dominating sets in the n X n rook graph. - Eric W. Weisstein, Jun 20 2017 and Aug 02 2017

References

  • A. M. Yaglom and I. M. Yaglom, Challenging Mathematical Problems with Elementary Solutions, Vol. 1: Combinatorial Analysis and Probability Theory, Dover Publications, 1987, p. 77

Crossrefs

Main diagonal of A290632 and of A368831.

Programs

Formula

a(n) = 2*n^n - n!.

A287065 Number of dominating sets on the n X n rook graph.

Original entry on oeis.org

1, 11, 421, 59747, 32260381, 67680006971, 559876911043381, 18412604442711949187, 2416403019417984915336061, 1267413006543912045144741284411, 2658304092145691708492995820522716981, 22300364428188338185156192161829091442585827
Offset: 1

Views

Author

Eric W. Weisstein, May 19 2017

Keywords

Comments

Number of {0,1} n X n matrices with no zero rows or no zero columns. - Geoffrey Critzer, Jan 15 2024

Crossrefs

Main diagonal of A287274.
Row sums of A368831.

Programs

  • Mathematica
    Table[(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}], {n, 20}] (* Eric W. Weisstein, May 27 2017 *)
  • PARI
    b(m,n)=sum(j=0, m, (-1)^j*binomial(m, j)*(2^(m - j) - 1)^n);
    a(n)=(2^n-1)^n + sum(i=1,n-1,b(n,i)*binomial(n,i)); \\ Andrew Howroyd, May 22 2017

Formula

a(n) = (2^n-1)^n + Sum_{i=1..n-1} binomial(n,i) * A183109(n,i). - Andrew Howroyd, May 22 2017

Extensions

a(6)-a(12) from Andrew Howroyd, May 22 2017
Showing 1-2 of 2 results.