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 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-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

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