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A225989 Number of pairs of orthogonal (-1,3) vectors of length 4*n. 1
20, 3192, 652784, 134432480, 28244153600, 6052498776192, 1314942362273280, 288501497813552640, 63776322167821168640, 14182989297327325110272, 3169467786802943379238912, 711136363409644515952173056 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Row 3 of A225987.

LINKS

R. H. Hardin, Table of n, a(n) for n = 1..145

EXAMPLE

Some solutions for n=1

.-1..3...-1..3....3..3...-1..3...-1..3...-1..3...-1..3...-1.-1....3..3...-1..3

..3..3...-1..3...-1..3....3..3...-1..3....3.-1...-1..3...-1.-1...-1..3....3.-1

.-1..3....3..3...-1..3....3.-1....3.-1....3..3...-1..3...-1.-1....3.-1....3..3

..3.-1....3.-1....3.-1...-1..3....3..3...-1..3....3..3...-1..3....3.-1....3.-1

CROSSREFS

Sequence in context: A250019 A145405 A028458 * A332265 A177323 A184891

Adjacent sequences:  A225986 A225987 A225988 * A225990 A225991 A225992

KEYWORD

nonn

AUTHOR

R. H. Hardin, May 22 2013

STATUS

approved

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Last modified May 8 13:26 EDT 2021. Contains 343666 sequences. (Running on oeis4.)