A319213 a(n) = phi(n^3 - 1)/3 where phi is A000010.

2, 4, 12, 20, 56, 36, 144, 96, 216, 144, 520, 240, 840, 480, 576, 816, 1568, 756, 2520, 1232, 1872, 1560, 4400, 1440, 4320, 3024, 4860, 3168, 7056, 2640, 9000, 5984, 7920, 6144, 10080, 4752, 17784, 7992, 13104, 9184, 22080, 7560, 23688, 12960, 14688, 15840, 33120

Offset

2,1

Links

Seiichi Manyama, Table of n, a(n) for n = 2..1000

Eric Weisstein's World of Mathematics, Totient Function.

Wikipedia, Euler's totient function.

Prog

(PARI) {a(n) = eulerphi(n^3-1)/3}

Crossrefs

Row 3 of A369291.

Cf. A000010, A068601 (n^3-1).

phi(n^b - 1)/b: A319210 (b=2), this sequence (b=3), A319214 (b=5).

Sequence in context: A297184 A218871 A121569 * A099603 A319615 A343865

Adjacent sequences: A319210 A319211 A319212 * A319214 A319215 A319216

Keyword

nonn

Author

Seiichi Manyama, Sep 13 2018

Status

approved