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A189393 a(n) = phi(n^4). 5
1, 8, 54, 128, 500, 432, 2058, 2048, 4374, 4000, 13310, 6912, 26364, 16464, 27000, 32768, 78608, 34992, 123462, 64000, 111132, 106480, 267674, 110592, 312500, 210912, 354294, 263424, 682892, 216000, 893730, 524288, 718740, 628864, 1029000, 559872 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,2

LINKS

Vincenzo Librandi and T. D. Noe, Table of n, a(n) for n = 1..1000 (Vincenzo Librandi to 680)

FORMULA

a(n) = n^3*phi(n).

Dirichlet g.f.: zeta(s - 4) / zeta(s - 3). The n-th term of the Dirichlet inverse is n^3 * A023900(n) = (-1)^omega(n) * a(n) / A003557(n), where omega=A001221. - Álvar Ibeas, Nov 24 2017

Sum_{k=1..n} a(k) ~ 6*n^5 / (5*Pi^2). - Vaclav Kotesovec, Feb 02 2019

MATHEMATICA

EulerPhi[Range[100]^4] (* T. D. Noe, Dec 27 2011 *)

PROG

(MAGMA) [ n^3*EulerPhi(n) : n in [1..100] ]

(PARI) vector(66, n, n^3*eulerphi(n))  /* Joerg Arndt, Apr 22 2011 */

CROSSREFS

Cf. A002618 (phi(n^2)), A053191 (phi(n^3)), A238533 (phi(n^5)), A239442 (phi(n^7)), A239443 (phi(n^9)).

Sequence in context: A070928 A180095 A234955 * A254951 A085537 A085540

Adjacent sequences:  A189390 A189391 A189392 * A189394 A189395 A189396

KEYWORD

nonn,easy,mult

AUTHOR

Vincenzo Librandi, Apr 21 2011

STATUS

approved

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Last modified November 14 22:17 EST 2019. Contains 329134 sequences. (Running on oeis4.)