Number of (3*n) X n matrices with nonnegative integer entries and each column sum being 3 up to permutation of rows.
A322487
Number of (3*n) X n matrices with nonnegative integer entries and each column sum being 3 up to permutation of rows.
Terms
- a(0) =1a(1) =3a(2) =31a(3) =686a(4) =27036a(5) =1688360a(6) =154703688a(7) =19692332568
External references
- oeis: A322487