A225993 Number of pairs of orthogonal (-1,5) vectors of length 6*n.

102, 211332, 720120000, 1722187940880, 4204143930847392, 11097567635368456704, 29480432084171748705792, 78401556201196275000295680, 210537848971493804380009055232, 569368618586592872585662539389952

Offset

1,1

Comments

Row 7 of A225987.

Links

R. H. Hardin, Table of n, a(n) for n = 1..91

Example

Some solutions for n=1
.-1..5...-1..5...-1..5...-1..5...-1..5...-1..5...-1..5...-1..5...-1..5...-1..5
.-1..5...-1..5...-1.-1...-1..5....5.-1...-1..5...-1..5....5..5....5.-1....5.-1
.-1..5...-1..5...-1.-1....5.-1....5.-1...-1..5....5..5...-1..5...-1..5....5..5
..5..5...-1..5...-1.-1....5..5...-1..5....5.-1...-1..5...-1..5...-1..5...-1..5
.-1..5....5..5...-1.-1...-1..5...-1..5....5.-1...-1..5....5.-1....5..5....5.-1
.-1..5....5.-1...-1.-1...-1..5....5..5....5..5....5.-1...-1..5....5.-1....5.-1

Crossrefs

Sequence in context: A097725 A353142 A129751 * A237432 A370404 A279242

Adjacent sequences: A225990 A225991 A225992 * A225994 A225995 A225996

Keyword

nonn

Author

R. H. Hardin, May 22 2013

Status

approved