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

Author

Michel Marcus, Sep 20 2018

Keywords

• nonn
• more

Links

• Tomohiro Yamada, An analog of perfect numbers involving the unitary totient function, arXiv:1806.00647 [math.NT], 2018. See (2) on p. 2.

Crossrefs

Cf. A047994.

A030163 is a subsequence.

Programs

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;