A050204 a(n) is the number of n X n matrices of 0's, 1's and -1's in which the entries in each row or column sum to 1.

1, 2, 21, 1344, 628080, 2030271480, 49846153939785, 9350902053107858880, 13807842729396124460629536, 162526525004284727135887319788800, 15464071313054035722739424623204673044920, 12011244510939290610945342901003078567310643860160

Offset

1,2

Links

Table of n, a(n) for n=1..12.

Crossrefs

Cf. A005130 (Robbins numbers).

Cf. A229165 (entries in each row or column sum to 1 and there are no adjacent -1's or 1's in any row or column).

Cf. A172645 (case row and column sums are zero).

Sequence in context: A022488 A264066 A052157 * A368188 A022470 A080815

Adjacent sequences: A050201 A050202 A050203 * A050205 A050206 A050207

Keyword

nonn

Author

Eric W. Weisstein

Extensions

Definition corrected by Murphy Waggoner and R. H. Hardin, Sep 24 2013

a(6)-a(8) from R. H. Hardin, Sep 25 2013

a(9)-a(12) from Andrew Howroyd, Feb 03 2021

Status

approved