A066300 Number of n X n matrices with exactly 2 1's in each row, other entries 0.

0, 1, 27, 1296, 100000, 11390625, 1801088541, 377801998336, 101559956668416, 34050628916015625, 13931233916552734375, 6831675453247426400256, 3955759092264800909058048, 2670419511272061205254504361

Offset

1,3

Links

Table of n, a(n) for n=1..14.

Formula

a(n) = binomial(n,2)^n.

Mathematica

Table[ Binomial[n, 2]^n, {n, 1, 16} ]

Prog

(PARI) a(n) = binomial(n, 2)^n \\ Charles R Greathouse IV, Dec 16 2016

Crossrefs

Cf. A001499.

Sequence in context: A104206 A327596 A163568 * A273518 A075547 A167732

Adjacent sequences: A066297 A066298 A066299 * A066301 A066302 A066303

Keyword

nonn

Author

Sharon Sela (sharonsela(AT)hotmail.com), Jan 01 2002

Extensions

More terms from Robert G. Wilson v, Jan 03 2002

Status

approved