A372662 a(n) = Sum_{i=1..n} Sum_{j=1..n} Sum_{k=1..n} phi(i*j*k) / phi(k).

1, 14, 72, 271, 731, 1649, 3417, 6654, 11495, 18635, 29971, 45088, 67562, 95862, 129315, 180548, 247178, 324463, 429785, 547025, 679318, 853788, 1080248, 1324791, 1617620, 1964622, 2361036, 2813206, 3392778, 3946537, 4704245, 5550066, 6389704, 7421750, 8455877

Offset: 1

Author

Seiichi Manyama, May 09 2024

Keywords

• nonn

Links

• Eric Weisstein's World of Mathematics, Totient Function.

Crossrefs

Cf. A000010, A372636, A372661, A372663.

Programs

Mathematica

Table[Sum[EulerPhi[i*j*k]/EulerPhi[k], {i, 1, n}, {j, 1, n}, {k, 1, n}], {n, 1, 40}] (* Vaclav Kotesovec, May 10 2024 *)

PARI

a(n) = sum(i=1, n, sum(j=1, n, sum(k=1, n, eulerphi(i*j*k)/eulerphi(k))));