A067214 Number of n X n 0..6 matrices with all row and column sums equal.
1, 7, 49, 5215, 21841937, 3430832678207, 21070560836988719941, 5258020825380244651432771257, 54855616345977485934984671841940089233
Offset: 0
Examples
Some solutions for n=3 ..4..0..6....5..4..4....1..2..4....5..5..2....5..0..4....6..3..0....2..6..2 ..3..5..2....6..4..3....0..5..2....1..5..6....0..6..3....0..6..3....3..4..3 ..3..5..2....2..5..6....6..0..1....6..2..4....4..3..2....3..0..6....5..0..5
Crossrefs
Column 6 of A202784.
Extensions
a(0)=1 prepended and a(6)-a(7) from Andrew Howroyd, May 11 2020
a(8) from Sean A. Irvine, Dec 12 2023