A225991 Number of pairs of orthogonal (-1,4) vectors of length 5*n.

45, 26010, 21594300, 15593341800, 11432293516320, 8690522384325600, 6699690552347865600, 5206881575348541978240, 4077143683681515029088000, 3212142498665023117259125760, 2542945288539007875744064972800

Offset

1,1

Comments

Row 5 of A225987.

Links

R. H. Hardin, Table of n, a(n) for n = 1..107

Example

Some solutions for n=1
.-1..4...-1..4....4..4...-1..4...-1..4...-1.-1...-1..4....4..4...-1..4...-1..4
..4..4...-1..4...-1..4....4.-1....4..4...-1.-1....4.-1...-1..4....4.-1....4..4
..4.-1...-1..4...-1..4....4.-1...-1..4...-1.-1....4..4...-1..4....4..4...-1..4
..4.-1....4..4...-1..4...-1..4...-1..4...-1..4...-1..4....4.-1....4.-1...-1..4
.-1..4...-1..4...-1..4....4..4...-1..4...-1.-1....4.-1....4.-1...-1..4....4.-1

Crossrefs

Sequence in context: A199521 A007537 A287434 * A125113 A354362 A003739

Adjacent sequences: A225988 A225989 A225990 * A225992 A225993 A225994

Keyword

nonn

Author

R. H. Hardin, May 22 2013

Status

approved