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%I #9 Feb 03 2021 20:09:27
%S 1,3,38,1107,58938,5002470,620355870,105848185590,23785613520480,
%T 6809213491925040,2419333087316808600,1044664066287091958400,
%U 538796052743780959419600,327150260492074733413299600,230994366606893955257329737600,187668642106165851767306588418000
%N Number of n-row matrices over {0,1,2} with all row and column sums equal to 1 or 2.
%D I. P. Goulden and D. M. Jackson, Combinatorial Enumeration, Wiley, N.Y., 1983,(Problem 3.4.15).
%H Andrew Howroyd, <a href="/A062155/b062155.txt">Table of n, a(n) for n = 0..100</a>
%e 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.
%o (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
%Y Row sums of A062154.
%Y Cf. A062156.
%K easy,nonn
%O 0,2
%A _Vladeta Jovovic_, Jun 06 2001
%E Terms a(14) and beyond from _Andrew Howroyd_, Feb 03 2021
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