A332686 - OEIS

A332686

a(n) = Sum_{k=1..n} phi(k/gcd(n, k)).

1, 2, 3, 5, 7, 9, 13, 18, 21, 23, 33, 33, 47, 49, 51, 67, 81, 76, 103, 97, 103, 119, 151, 135, 163, 173, 185, 189, 243, 185, 279, 280, 265, 299, 291, 291, 397, 379, 369, 371, 491, 381, 543, 491, 455, 553, 651, 539, 653, 610, 643, 683, 831, 689, 743, 753, 801, 887, 1029

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OFFSET

1,2

COMMENTS

Inverse Moebius transform of A053570.

LINKS

Seiichi Manyama, Table of n, a(n) for n = 1..10000

FORMULA

a(n) = Sum_{k=1..n} phi(lcm(n, k)/n).

a(n) = Sum_{d|n} A053570(d).

MATHEMATICA

Table[Sum[EulerPhi[k/GCD[n, k]], {k, 1, n}], {n, 1, 59}]