A225992 Number of pairs of orthogonal (-3,4) vectors of length 7*n.

420, 8168160, 106322711040, 1496349265582080, 22046445329510891520, 329200486775643608186880, 4991630444756812041482665984, 76438688358604087005593563299840, 1179634366672136518672486151133069312

Offset: 1

Author

R. H. Hardin, May 22 2013

Keywords

• nonn

Comments

Row 6 of A225987.

Examples

			Some solutions for n=1
.-3..4...-3..4...-3..4...-3..4....4..4...-3..4....4..4...-3.-3...-3.-3....4..4
.-3..4....4..4...-3.-3....4..4...-3..4....4.-3...-3..4...-3.-3...-3.-3....4..4
.-3..4....4.-3...-3.-3....4..4....4..4....4..4....4..4...-3..4...-3..4...-3..4
..4..4....4..4...-3..4...-3..4...-3..4....4.-3...-3..4...-3..4...-3..4....4.-3
..4.-3....4.-3...-3.-3....4.-3....4.-3...-3..4....4..4....4.-3...-3.-3...-3..4
..4..4...-3..4...-3.-3....4..4....4..4....4..4....4.-3...-3.-3...-3.-3....4..4
..4..4....4..4...-3..4...-3..4....4.-3....4..4...-3..4...-3.-3...-3..4....4.-3
		

Links

• R. H. Hardin, Table of n, a(n) for n = 1..64