|
%I #7 Sep 06 2013 02:04:54
%S 20,3192,652784,134432480,28244153600,6052498776192,1314942362273280,
%T 288501497813552640,63776322167821168640,14182989297327325110272,
%U 3169467786802943379238912,711136363409644515952173056
%N Number of pairs of orthogonal (-1,3) vectors of length 4*n.
%C Row 3 of A225987.
%H R. H. Hardin, <a href="/A225989/b225989.txt">Table of n, a(n) for n = 1..145</a>
%e Some solutions for n=1
%e .-1..3...-1..3....3..3...-1..3...-1..3...-1..3...-1..3...-1.-1....3..3...-1..3
%e ..3..3...-1..3...-1..3....3..3...-1..3....3.-1...-1..3...-1.-1...-1..3....3.-1
%e .-1..3....3..3...-1..3....3.-1....3.-1....3..3...-1..3...-1.-1....3.-1....3..3
%e ..3.-1....3.-1....3.-1...-1..3....3..3...-1..3....3..3...-1..3....3.-1....3.-1
%K nonn
%O 1,1
%A _R. H. Hardin_, May 22 2013
| 