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A290793 Carmichael numbers n such that Euler totient function of n (phi(n)) is a cube. 2
63973, 18162001, 26921089, 133205761, 225745345, 490503601, 496050841, 698548201, 1031750401, 1100674561, 1384157161, 2178944461, 3805181281, 11351100241, 12648201841, 26498875681, 26542598401, 28553256865, 28645206001, 37590868801, 39866123377, 40527674881 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,1

COMMENTS

Banks proved that for each positive integer N there are an infinite number of Carmichael numbers whose Euler totient function value is an N-th power. Therefore this sequence is infinite.

The terms were calculated using Pinch's tables of Carmichael numbers (see link below).

LINKS

Amiram Eldar, Table of n, a(n) for n = 1..2942 (terms below 10^18)

William D. Banks, Carmichael Numbers with a Square Totient, Canadian Mathematical Bulletin, Vol. 52, No. 1 (2009), pp. 3-8.

R. G. E. Pinch, Tables relating to Carmichael numbers.

EXAMPLE

phi(63973) = 36^3.

MATHEMATICA

With[{s = Import["b002997.txt", "Data"][[All, -1]]}, Select[s, IntegerQ@ Power[EulerPhi@ #, 1/3] &]] (* Michael De Vlieger, Aug 14 2017, using b-file at A002997 *)

CROSSREFS

Intersection of A002997 (Carmichael numbers) and A039771.

Cf. A000010, A000578, A272798.

Sequence in context: A214758 A265827 A212882 * A182518 A317136 A182089

Adjacent sequences:  A290790 A290791 A290792 * A290794 A290795 A290796

KEYWORD

nonn

AUTHOR

Amiram Eldar, Aug 10 2017

STATUS

approved

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Last modified December 4 12:41 EST 2021. Contains 349519 sequences. (Running on oeis4.)