A184274 Number of distinct n X 3 toroidal 0..3 arrays.

24, 700, 29184, 1398500, 71582944, 3817765120, 209430787824, 11728124734500, 667199944873344, 38430716856090160, 2235968978631715024, 131176846748291651840, 7749524484709164817824, 460543169377106318541400, 27509778650786228522002432

Offset: 1

Author

R. H. Hardin, Jan 10 2011

Keywords

• nonn

Links

• Andrew Howroyd, Table of n, a(n) for n = 1..100

Crossrefs

Column 3 of A184277.

Programs

Mathematica

T[n_, k_] := (1/(n*k))*Sum[Sum[EulerPhi[c]*EulerPhi[d]*4^(n*k/LCM[c, d]), {d, Divisors[k]}], {c, Divisors[n]}]; a[n_] := T[n, 3]; Array[a, 15] (* Jean-François Alcover, Oct 31 2017, after Andrew Howroyd *)

Extensions

Terms a(9) and beyond from Andrew Howroyd, Sep 27 2017