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 A055602 Number of n X n binary matrices with no 0 rows or columns and with n+1 1's. 9
 0, 4, 45, 432, 4200, 43200, 476280, 5644800, 71850240, 979776000, 14270256000, 221298739200, 3642807168000, 63465795993600, 1167099373440000, 22596613079040000, 459548157100032000, 9795631769763840000 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,2 LINKS Robert Israel, Table of n, a(n) for n = 1..445 FORMULA Number of m X n binary matrices with no zero rows or columns and with k=0..m*n ones is Sum_{i=0..n} (-1)^i*binomial(n, i)*a(m, n-i, k) where a(m, n, k)=Sum_{i=0..m} (-1)^i*binomial(m, i)*binomial((m-i)*n, k). a(n) = n*(n-1)*(n+2)*n!/4. - Vladeta Jovovic, Mar 25 2006 From Robert Israel, May 04 2021: (Start) E.g.f.: x^2*(4-x)/(2*(1-x)^2). D-finite with recurrence 4*(n-2)*a(n)-n*(4*n+3)*a(n-1)-(n-1)^2*a(n-2)=0. (End) MAPLE f:= n -> n*(n-1)*(n+2)*n!/4: map(f, [\$1..30]); # Robert Israel, May 04 2021 CROSSREFS A diagonal of triangle A104601. Cf. A055603. Sequence in context: A343904 A117644 A232729 * A346629 A073565 A039657 Adjacent sequences: A055599 A055600 A055601 * A055603 A055604 A055605 KEYWORD nonn AUTHOR Vladeta Jovovic, Jun 01 2000 EXTENSIONS More terms from David Wasserman, Apr 28 2002 STATUS approved

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Last modified March 3 06:28 EST 2024. Contains 370499 sequences. (Running on oeis4.)