A225994 Number of pairs of orthogonal (-2,5) vectors of length 7*n.

378, 5133128, 81705087744, 983771662124160, 13027612739061516288, 180842352214339004973056, 2505372582582745606695616512, 35065654463193295271305370959872, 495605164965018396615832445084368896

Offset

1,1

Comments

Row 8 of A225987.

Links

R. H. Hardin, Table of n, a(n) for n = 1..78

Example

Some solutions for n=1
.-2..5...-2..5...-2..5...-2..5....5..5...-2..5....5..5....5..5...-2..5...-2..5
.-2..5....5..5....5.-2...-2..5....5..5....5..5...-2..5...-2..5....5..5....5.-2
..5..5...-2..5....5.-2....5.-2...-2..5....5.-2....5.-2....5.-2....5.-2....5..5
.-2..5...-2..5....5.-2....5.-2...-2..5....5..5...-2..5....5..5....5.-2....5..5
..5.-2....5.-2....5.-2....5..5....5.-2....5.-2...-2..5...-2..5....5.-2...-2..5
..5..5....5..5....5..5....5.-2...-2..5....5.-2....5.-2....5.-2....5.-2...-2..5
..5.-2....5.-2....5..5....5..5...-2..5...-2..5....5..5....5.-2....5..5...-2..5

Crossrefs

Sequence in context: A289347 A171115 A328552 * A228554 A108385 A341188

Adjacent sequences: A225991 A225992 A225993 * A225995 A225996 A225997

Keyword

nonn

Author

R. H. Hardin, May 22 2013

Status

approved