A188895 - OEIS

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A188895

Number of n X n (real) {-1,1}-matrices having determinant A003433(n).

3

1, 4, 96, 384, 30720, 7372800, 4335206400, 2477260800, 25684239974400, 7191587192832000

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OFFSET

0,2

LINKS

Table of n, a(n) for n=0..9.

Minfeng Wang, C++ program to calculate a(2) .. a(5)

Eric Weisstein's World of Mathematics, Hadamard's Maximum Determinant Problem

Eric Weisstein's World of Mathematics, (-1, 1)-Matrix

FORMULA

a(n) = 2^(2n+1) * A051752(n) for n>=2. - Hugo Pfoertner and Minfeng Wang, Jan 22 2023

CROSSREFS

Cf. A003433, A051752.

Sequence in context: A220682 A210926 A302121 * A068114 A272109 A203316

Adjacent sequences: A188892 A188893 A188894 * A188896 A188897 A188898

KEYWORD

nonn,more,hard

AUTHOR

Eric W. Weisstein, Apr 19 2011

EXTENSIONS

Offset changed to 0 by Hugo Pfoertner, Jan 23 2023

a(5)-a(9) from Minfeng Wang, Jan 22 2023

STATUS

approved