A319481 Integers k such that uphi(k) divides k, where uphi is the unitary phi function (A047994).

1, 2, 6, 12, 168, 240, 14880, 65280, 4294901760, 7608944640, 1125874137169920, 18446744069414584320

Offset

1,2

Links

Table of n, a(n) for n=1..12.

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

Adjacent sequences: A319478 A319479 A319480 * A319482 A319483 A319484

Keyword

nonn,more

Author

Michel Marcus, Sep 20 2018

Status

approved