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A225990 Number of pairs of orthogonal (-2,3) vectors of length 5*n. 1
60, 48720, 41801760, 36951200000, 33792065269760, 31520952625612800, 29804588641610956800, 28466071692659367936000, 27397648707462915867279360, 26530254119576872937974661120, 25817362047962660055225414451200 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Row 4 of A225987.

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..115

EXAMPLE

Some solutions for n=1

.-2..3...-2..3...-2..3....3..3...-2.-2...-2..3...-2.-2...-2.-2...-2..3...-2..3

.-2..3....3.-2....3..3...-2..3...-2..3...-2..3...-2..3...-2..3....3.-2....3.-2

..3..3....3..3...-2..3...-2..3...-2.-2...-2..3...-2.-2...-2.-2....3..3...-2..3

.-2..3....3..3....3..3....3..3...-2..3....3..3...-2.-2....3.-2....3..3....3..3

..3..3....3.-2...-2..3....3.-2...-2.-2....3..3....3.-2...-2.-2...-2..3....3..3

CROSSREFS

Sequence in context: A220371 A092870 A221936 * A185560 A003788 A222019

Adjacent sequences:  A225987 A225988 A225989 * A225991 A225992 A225993

KEYWORD

nonn

AUTHOR

R. H. Hardin, May 22 2013

STATUS

approved

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Last modified January 25 05:34 EST 2022. Contains 350565 sequences. (Running on oeis4.)