OFFSET
1,2
LINKS
Joerg Arndt, Table of n, a(n) for n = 1..500
MATHEMATICA
gg[n_] := gg[n] = Flatten[Table[{{x, y}, {z, t}}, {x, n}, {y, n}, {t, n}, {z, n}], 3]; nil[n_] := nil[n] = Length@gg[n][[Select[Range[Length[gg[n]]], Mod[gg[n][[#]].Transpose[gg[n][[#]]], n] == {{0, 0}, {0, 0}} &]]]; Table[Print[nil[n]]; nil[n], {n, 1, 22}]
CROSSREFS
KEYWORD
nonn,mult
AUTHOR
José María Grau Ribas, Mar 08 2012
EXTENSIONS
Keyword:mult added by Andrew Howroyd, Aug 02 2018
STATUS
approved