A372669 a(n) = Sum_{j=1..n} Sum_{k=1..n} phi(n*j*k) / phi(n*k).

1, 6, 16, 37, 62, 121, 154, 256, 339, 499, 560, 884, 910, 1308, 1516, 1870, 1979, 2889, 2756, 3776, 4023, 4814, 4795, 6716, 6330, 7908, 8301, 9946, 9520, 13406, 11587, 14598, 15236, 17508, 17438, 22182, 19518, 24329, 24855, 29063, 26521, 35789, 30577, 37769

Offset

1,2

Links

Table of n, a(n) for n=1..44.

Mathematica

Table[Sum[EulerPhi[n*j*k] / EulerPhi[n*k], {j, 1, n}, {k, 1, n}], {n, 1, 50}] (* Vaclav Kotesovec, May 10 2024 *)

Prog

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

Crossrefs

Cf. A000010, A070639, A372668.

Sequence in context: A048487 A124699 A237601 * A064602 A360650 A346375

Adjacent sequences: A372666 A372667 A372668 * A372670 A372671 A372672

Keyword

nonn

Author

Seiichi Manyama, May 09 2024

Status

approved