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A225990 Number of pairs of orthogonal (-2,3) vectors of length 5*n. 1

%I

%S 60,48720,41801760,36951200000,33792065269760,31520952625612800,

%T 29804588641610956800,28466071692659367936000,

%U 27397648707462915867279360,26530254119576872937974661120,25817362047962660055225414451200

%N Number of pairs of orthogonal (-2,3) vectors of length 5*n.

%C Row 4 of A225987.

%H R. H. Hardin, <a href="/A225990/b225990.txt">Table of n, a(n) for n = 1..115</a>

%e Some solutions for n=1

%e .-2..3...-2..3...-2..3....3..3...-2.-2...-2..3...-2.-2...-2.-2...-2..3...-2..3

%e .-2..3....3.-2....3..3...-2..3...-2..3...-2..3...-2..3...-2..3....3.-2....3.-2

%e ..3..3....3..3...-2..3...-2..3...-2.-2...-2..3...-2.-2...-2.-2....3..3...-2..3

%e .-2..3....3..3....3..3....3..3...-2..3....3..3...-2.-2....3.-2....3..3....3..3

%e ..3..3....3.-2...-2..3....3.-2...-2.-2....3..3....3.-2...-2.-2...-2..3....3..3

%K nonn

%O 1,1

%A _R. H. Hardin_, May 22 2013

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Last modified May 20 15:47 EDT 2022. Contains 353874 sequences. (Running on oeis4.)