A058810 The sequence lambda(n,n), where lambda is defined in A055203.

1, 0, 1, 24, 978, 63540, 6075900, 805351680, 141497266680, 31843424440800, 8934902572138200, 3058578720594936000, 1254725049041097480000, 607696683874925162918400, 343106914496426524661817600, 223382333871697909676511744000, 166127588708309626930142410800000

Offset: 0

Author

N. J. A. Sloane, Jan 03 2001

Keywords

• nonn

Comments

Number of n X n binary matrices with 2 ones in every column and no empty rows. - Andrew Howroyd, Dec 15 2018

Links

• Andrew Howroyd, Table of n, a(n) for n = 0..100

Crossrefs

Cf. A055203.

Programs

Mathematica

a[0]=1; a[n_] := Sum[(-1)^(n-i)((i-1)i)^n Binomial[n, i], {i, 0, n}]/2^n;
Array[a, 17, 0] (* Jean-François Alcover, Aug 27 2019 *)

PARI

a(n)=sum(i=0, n, (-1)^(n-i)*binomial(n,i)*binomial(i,2)^n) \\ Andrew Howroyd, Dec 15 2018

Formula

a(n) = Sum_{i=0..n} (-1)^(n-i)*binomial(n,i)*binomial(i,2)^n. - Andrew Howroyd, Dec 15 2018

Extensions

a(0)=1 prepended by Andrew Howroyd, Dec 15 2018