OFFSET
0,2
REFERENCES
I. P. Goulden and D. M. Jackson, Combinatorial Enumeration, Wiley, N.Y., 1983,(Problem 3.4.15).
LINKS
Andrew Howroyd, Table of n, a(n) for n = 0..100
EXAMPLE
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.
PROG
(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
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Vladeta Jovovic, Jun 06 2001
EXTENSIONS
Terms a(14) and beyond from Andrew Howroyd, Feb 03 2021
STATUS
approved