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A319481 Integers k such that uphi(k) divides k, where uphi is the unitary phi function (A047994). 3
1, 2, 6, 12, 168, 240, 14880, 65280, 4294901760, 7608944640, 1125874137169920, 18446744069414584320 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,2
LINKS
Tomohiro Yamada, An analog of perfect numbers involving the unitary totient function, arXiv:1806.00647 [math.NT], 2018. See (2) on p. 2.
PROG
(PARI) uphi(n) = my(f=factor(n)~); prod(i=1, #f, f[1, i]^f[2, i]-1);
isok(n) = frac(n/uphi(n)) == 0;
CROSSREFS
Cf. A047994.
A030163 is a subsequence.
Sequence in context: A193619 A290406 A371042 * A195338 A179201 A105122
KEYWORD
nonn,more
AUTHOR
Michel Marcus, Sep 20 2018
STATUS
approved

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Last modified March 29 04:23 EDT 2024. Contains 371264 sequences. (Running on oeis4.)