A372663 a(n) = Sum_{i=1..n} Sum_{j=1..n} Sum_{k=1..n} phi(i*j*k) / phi(j*k).

1, 11, 46, 139, 316, 633, 1138, 1947, 3060, 4583, 6660, 9367, 12856, 17153, 22169, 28886, 36843, 46179, 57402, 70096, 84177, 101268, 121333, 143664, 168513, 197084, 228759, 263965, 304686, 346832, 396697, 452114, 508358, 573205, 638715, 714691, 799950, 890893, 984275

Offset

1,2

Links

Table of n, a(n) for n=1..39.

Eric Weisstein's World of Mathematics, Totient Function.

Mathematica

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

Prog

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

Crossrefs

Cf. A000010, A372661, A372662.

Sequence in context: A224142 A155014 A006324 * A256582 A231887 A302449

Adjacent sequences: A372660 A372661 A372662 * A372664 A372665 A372666

Keyword

nonn

Author

Seiichi Manyama, May 09 2024

Status

approved