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

0,4

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

Formula

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

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 *)

Prog

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

Crossrefs

Cf. A055203.

Sequence in context: A174586 A254619 A006175 * A265872 A223147 A272551

Adjacent sequences: A058807 A058808 A058809 * A058811 A058812 A058813

Keyword

nonn

Author

N. J. A. Sloane, Jan 03 2001

Extensions

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

Status

approved