A335776 Number of idempotent non-symmetric n X n (0,1)-matrices over the reals.

0, 0, 4, 42, 436, 5650, 96544, 2185610, 65108236

Offset

0,3

Comments

Off diagonal entries of an idempotent symmetric n X n (0,1)-matrix must be zero.

Links

Table of n, a(n) for n=0..8.

Formula

a(n) = A086922(n) - A000079(n).

Example

a(2) = 4 because [1,1]  [0,1]  [0,0]  [1,0]
                 [0,0], [0,1], [1,1], [1,0], are non-symmetric and idemponent.

Crossrefs

Cf. A000079, A086922.

Sequence in context: A085954 A046719 A366819 * A092800 A370282 A268542

Adjacent sequences: A335773 A335774 A335775 * A335777 A335778 A335779

Keyword

nonn,more

Author

Torlach Rush, Jun 22 2020

Status

approved