A223453 T(n,k) = Number of idempotent n X n -k..k matrices.

2, 2, 12, 2, 28, 164, 2, 44, 848, 5712, 2, 60, 1928, 102432, 407072, 2, 76, 3752, 462464

Offset

1,1

Comments

Table starts

......2......2......2....2..2.2

.....12.....28.....44...60.76

....164....848...1928.3752

...5712.102432.462464

.407072

Links

Table of n, a(n) for n=1..19.

Example

Some solutions for n=3 k=4
.-2.-1..4....0..0..0....0..0..0....0..0..2....1.-1.-1....4..3..0....0.-1..1
.-2.-1..4...-1..1..0....3..1..0....0..1..0....0.-2.-3...-4.-3..0....2..3.-2
.-2.-1..4....3..0..1...-3.-1..0....0..0..1....0..2..3....4..4..1....2..2.-1

Crossrefs

Cf. A223454, A223455.

Sequence in context: A286464 A380459 A058044 * A285729 A293231 A286152

Adjacent sequences: A223450 A223451 A223452 * A223454 A223455 A223456

Keyword

nonn,tabl,more

Author

R. H. Hardin, Apr 09 2013

Status

approved