A331717 Number of nonequivalent n-column binary matrices with 2 ones in every column and any number of distinct nonzero rows up to permutation of rows and columns.

1, 0, 1, 4, 12, 36, 124, 412, 1500

Offset: 0

Author

Andrew Howroyd, Feb 02 2020

Keywords

• nonn
• more

Examples

			The a(3) = 4 matrices are:
  [1 1 1]  [1 1 0]  [1 1 1]  [1 1 0]
  [1 0 0]  [1 0 1]  [1 1 0]  [1 0 1]
  [0 1 0]  [0 1 0]  [0 0 1]  [0 1 1]
  [0 0 1]  [0 0 1]
		

Crossrefs

Row n=2 of A331510.

Cf. A331718.