

A333902


Number of nonequivalent 3 X n nonnegative integer matrices with all column sums 3 and row sums n up to permutation of rows.


2



1, 1, 2, 10, 70, 566, 4781, 41357, 364470, 3257830, 29450557, 268701797, 2470513849, 22862694505, 212758007450, 1989477010250, 18682005254390, 176085344355510, 1665167298000005, 15793406377949405, 150192477267201945, 1431741484334863145, 13678227386467491410
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OFFSET

0,3


COMMENTS

Number of factorizations of m^3 into 3 factors, where m is a product of exactly n distinct primes and each factor is a product of n primes (counted with multiplicity).


LINKS



EXAMPLE

The a(2) = 2 matrices are:
[1 1] [0 2]
[1 1] [1 1]
[1 1] [2 0]


CROSSREFS



KEYWORD

nonn


AUTHOR



STATUS

approved



