A226000 Number of pairs of orthogonal (-2,7) vectors of length 9*n.

2376, 473173920, 142896990300480, 20278050662801226240, 3273835406669841316064256, 637732143080315479532514447360, 115448330868966954716300528059883520

Offset

1,1

Comments

Row 14 of A225987.

Links

R. H. Hardin, Table of n, a(n) for n = 1..46

Example

Some solutions for n=1
.-2..7...-2..7...-2..7...-2..7...-2..7...-2..7....7..7...-2..7...-2..7....7..7
..7.-2....7.-2....7.-2....7..7....7..7....7..7...-2..7....7.-2...-2..7...-2..7
.-2..7...-2..7....7..7...-2..7...-2..7...-2..7....7.-2....7..7....7..7...-2..7
..7..7....7..7...-2..7...-2..7....7.-2....7.-2....7..7...-2..7...-2..7....7.-2
.-2..7....7.-2...-2..7...-2..7....7.-2....7..7...-2..7....7.-2....7.-2...-2..7
..7..7...-2..7....7..7...-2..7...-2..7....7.-2...-2..7....7..7...-2..7....7..7
..7.-2....7.-2...-2..7...-2..7....7.-2....7.-2....7.-2....7.-2...-2..7...-2..7
.-2..7....7..7....7.-2....7..7....7..7...-2..7...-2..7....7.-2...-2..7...-2..7
.-2..7...-2..7....7.-2...-2..7...-2..7...-2..7....7.-2....7.-2....7..7...-2..7

Crossrefs

Sequence in context: A250588 A165948 A183599 * A163026 A069300 A255800

Adjacent sequences: A225997 A225998 A225999 * A226001 A226002 A226003

Keyword

nonn

Author

R. H. Hardin, May 22 2013

Status

approved