A280907 Least k such that cototient(k) has exactly n distinct prime factors.

4, 10, 42, 294, 3462, 45042, 760446, 14549526, 289194150, 8729875770

Offset

1,1

Comments

Least k such that A001221(A051953(k)) = n.

Links

Table of n, a(n) for n=1..10.

Example

a(1) = 4 because 4 - phi(4) = 2.
a(2) = 10 because 10 - phi(10) = 6 = 2 * 3.
a(3) = 42 because 42 - phi(42) = 30 = 2 * 3 * 5.

Prog

(PARI) a(n) = {my(k = 2); while(omega(k-eulerphi(k)) != n, k++); k; }

Crossrefs

Cf. A001221, A051953.

Sequence in context: A361938 A222475 A194993 * A380530 A372648 A332233

Adjacent sequences: A280904 A280905 A280906 * A280908 A280909 A280910

Keyword

nonn,more

Author

Altug Alkan, Jan 10 2017

Extensions

a(10) from Amiram Eldar, Sep 13 2024

Status

approved