A333902 Number of nonequivalent 3 X n nonnegative integer matrices with all column sums 3 and row sums n up to permutation of rows.

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

Offset: 0

Author

Andrew Howroyd, Apr 18 2020

Keywords

• nonn

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).

Examples

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

Links

• Andrew Howroyd, Table of n, a(n) for n = 0..100

Crossrefs

Row n=3 of A257462.