A145675 - OEIS

A145675

Number of n X n {0,-1,1}-matrices A such that permanent( |A| ) = | det A |, where |A| is obtained from A by taking the absolute value of each entry.

1, 3, 73, 12787, 13698241 (list; graph; refs; listen; history; text; internal format)

	OFFSET	`0,2`
	COMMENTS	`Also the number of n X n sign-nonsingular matrices (see reference for definition).`
	REFERENCES	`Brualdi, Richard A. and Shader, Bryan L., On sign-nonsingular matrices and the conversion of the permanent into the determinant, in Applied Geometry and Discrete Mathematics (The Victor Klee Festschrift), pp. 117-134, DIMACS Ser. Discrete Math. Theoret. Comput. Sci., 4, Amer. Math. Soc., Providence, RI, 1991.`
	LINKS	`Table of n, a(n) for n=0..4.`
	CROSSREFS	`Cf. A145676.` `Sequence in context: A119017 A307232 A002667 * A336873 A121981 A337413` `Adjacent sequences: A145672 A145673 A145674 * A145676 A145677 A145678`
	KEYWORD	`nonn`
	AUTHOR	`N. J. A. Sloane, Mar 26 2009`
	EXTENSIONS	`a(1)-a(4) computed by Eric W. Weisstein, Mar 26, 2009`
	STATUS	`approved`

Last modified March 22 20:34 EDT 2023. Contains 361433 sequences. (Running on oeis4.)