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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. 4
1, 2, 21, 1344, 628080, 2030271480, 49846153939785, 9350902053107858880 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Table of n, a(n) for n=1..8.

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).

Sequence in context: A022488 A264066 A052157 * A022470 A080815 A276654

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

STATUS

approved

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Last modified November 16 00:11 EST 2018. Contains 317252 sequences. (Running on oeis4.)