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A172579 Number of 4*n X n 0..1 arrays with row sums 2 and column sums 8 1
0, 1, 34650, 27770358330, 149144498504001000, 3776577900841430197548750, 352231966693098849132080247442500, 101028698009849992018229820380077899975000 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,3

LINKS

R. H. Hardin, Table of n, a(n) for n=1..24

Gao, Shanzhen, and Matheis, Kenneth, Closed formulas and integer sequences arising from the enumeration of (0,1)-matrices with row sum two and some constant column sums. In Proceedings of the Forty-First Southeastern International Conference on Combinatorics, Graph Theory and Computing. Congr. Numer. 202 (2010), 45-53. MR2762458

FORMULA

a(n) = ((4n)!/2^(4n))*Sum_{i=0..n} Sum_{j=0..n-i} Sum_{k=0..n-i-j} Sum_{t=0..n-i-j-k} (n!/(i!j!k!t!(n-i-j-k-t)!))*((-1)^(-3j-2k-t+4n-4i)/(4n+3j+2k+t-4n+4i)!)*((8i+6j+4k+2t)!/((8!)^i*(6!)^j*48^k*12^t*24^(n-i-j-k-t))). - Shanzhen Gao, Feb 16 2010

CROSSREFS

Sequence in context: A081428 A237955 A023336 * A172570 A172672 A172770

Adjacent sequences:  A172576 A172577 A172578 * A172580 A172581 A172582

KEYWORD

nonn

AUTHOR

R. H. Hardin, Feb 06 2010

STATUS

approved

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Last modified August 9 09:14 EDT 2022. Contains 356021 sequences. (Running on oeis4.)