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A172616 Number of 9*n X 2*n 0..1 arrays with row sums 2 and column sums 9. 1
1, 842090474940, 9561215418596022668009737500, 41499275921837441873503310658937755719615400000, 15806556884633733578544972910460376919497070823113887278535399000000 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

REFERENCES

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.

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..11

CROSSREFS

Sequence in context: A323533 A233800 A162027 * A233487 A297354 A172798

Adjacent sequences:  A172613 A172614 A172615 * A172617 A172618 A172619

KEYWORD

nonn

AUTHOR

R. H. Hardin, Feb 06 2010

EXTENSIONS

Incorrect formula removed by Jon E. Schoenfield, Jan 22 2018

STATUS

approved

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Last modified November 30 03:03 EST 2021. Contains 349416 sequences. (Running on oeis4.)