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A062155
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Number of n-row matrices over {0,1,2} with all row and column sums equal to 1 or 2.
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3
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1, 3, 38, 1107, 58938, 5002470, 620355870, 105848185590, 23785613520480, 6809213491925040, 2419333087316808600, 1044664066287091958400, 538796052743780959419600, 327150260492074733413299600, 230994366606893955257329737600, 187668642106165851767306588418000
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OFFSET
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0,2
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REFERENCES
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I. P. Goulden and D. M. Jackson, Combinatorial Enumeration, Wiley, N.Y., 1983,(Problem 3.4.15).
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LINKS
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EXAMPLE
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There are 38 2-row matrices over {0,1,2} with all row and column sums equal to 1 or 2: 1 of type 2 X 1, 13 of type 2 X 2, 18 of type 2 X 3 and 6 of type 2 X 4, cf. A062154.
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PROG
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(PARI) seq(n)={[subst(serlaplace(p), y, 1) | p <- Vec(serlaplace(1/sqrt(1-x*y + O(x*x^n))*exp(x*y/2+1/(1-x*y)*(x*y+x^2*y/2+x*y^2/2) + O(x*x^n))))]} \\ Andrew Howroyd, Feb 03 2021
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CROSSREFS
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KEYWORD
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easy,nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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