A333899 Number of nonequivalent n X n binary matrices with 3 ones in every row and column up to permutation of rows.

1, 0, 0, 1, 1, 22, 550, 16700, 703297, 38135272, 2584332084, 214050246975, 21269928579625, 2497135296996934, 341930210261762434, 54008226638062039798, 9746833030828647070625, 1993080976749664740373600, 458405276998431265342151848, 117814680468332544208002721773

Offset

0,6

Comments

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

Links

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

Crossrefs

Column k=3 of A260340.

Cf. A254243.

Sequence in context: A320766 A203456 A271266 * A239652 A223883 A223890

Adjacent sequences: A333896 A333897 A333898 * A333900 A333901 A333902

Keyword

nonn

Author

Andrew Howroyd, Apr 18 2020

Status

approved