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A319213
a(n) = phi(n^3 - 1)/3 where phi is A000010.
5
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
Eric Weisstein's World of Mathematics, Totient Function.
MATHEMATICA
EulerPhi[Range[2, 50]^3 - 1]/3 (* Paolo Xausa, Jun 18 2024 *)
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 A375742
KEYWORD
nonn
AUTHOR
Seiichi Manyama, Sep 13 2018
STATUS
approved