A184287 Number of distinct n X 4 toroidal 0..4 arrays.

165, 49075, 20346485, 9536816875, 4768372070757, 2483526896194175, 1330460821097243445, 727595761432647851875, 404219867454740749892485, 227373675443239212037148635, 129189588320018269798974609525, 74014868308343773086872161914375

Offset

1,1

Links

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

Mathematica

T[n_, k_] := (1/(n*k))*Sum[Sum[EulerPhi[c]*EulerPhi[d]*5^(n*k/LCM[c, d]), {d, Divisors[k]}], {c, Divisors[n]}]; a[n_] := T[n, 4]; Array[a, 12] (* Jean-François Alcover, Nov 01 2017, after Andrew Howroyd *)

Prog

(PARI) a(n) = my(k=4); (1/(n*k)) * sumdiv(n, c, sumdiv(k, d, eulerphi(c) * eulerphi(d) * 5^(n*k/lcm(c, d)))); \\ Michel Marcus, Nov 01 2017

Crossrefs

Column 4 of A184288.

Sequence in context: A273441 A046178 A176018 * A233466 A203183 A184128

Adjacent sequences: A184284 A184285 A184286 * A184288 A184289 A184290

Keyword

nonn

Author

R. H. Hardin, Jan 10 2011

Extensions

Terms a(6) and beyond from Andrew Howroyd, Sep 27 2017

Status

approved