login
The OEIS Foundation is supported by donations from users of the OEIS and by a grant from the Simons Foundation.

 

Logo


Hints
(Greetings from The On-Line Encyclopedia of Integer Sequences!)
A058810 The sequence lambda(n,n), where lambda is defined in A055203. 1
1, 0, 1, 24, 978, 63540, 6075900, 805351680, 141497266680, 31843424440800, 8934902572138200, 3058578720594936000, 1254725049041097480000, 607696683874925162918400, 343106914496426524661817600, 223382333871697909676511744000, 166127588708309626930142410800000 (list; graph; refs; listen; history; text; internal format)
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-Fran├žois 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

Lookup | Welcome | Wiki | Register | Music | Plot 2 | Demos | Index | Browse | More | WebCam
Contribute new seq. or comment | Format | Style Sheet | Transforms | Superseeker | Recent
The OEIS Community | Maintained by The OEIS Foundation Inc.

License Agreements, Terms of Use, Privacy Policy. .

Last modified May 28 03:04 EDT 2020. Contains 334671 sequences. (Running on oeis4.)