A096996 a(n) is the smallest initial value if function f(x)=sigma(phi(x))=A062402(x) is iterated and the iteration ends in a cycle of length n.

1, 5, 17, 401

Offset

1,2

Comments

a(5) exists and <= 2^80.

a(6) = 883, a(11) = 88897, a(15) = 470137, a(18) = 448181;

a(9) = 24877841, a(12) = 16295171, a(21) <= 726569551. 254808457 does not reach a cycle after 14000 iterations. - Hiroaki Yamanouchi, Sep 06 2014

a(5) <= 9248288975491. - Hiroaki Yamanouchi, Sep 10 2014

a(5) > 8.5*10^7. - Tyler Busby, Mar 29 2024

Links

Table of n, a(n) for n=1..4.

Example

a(4) = 401. 401 -> 961 -> 2304 -> 2044 -> 2520 -> 1651 -> 4800 -> 3066 -> 2520 (cycle length = 4). - Hiroaki Yamanouchi, Sep 06 2014

Crossrefs

Cf. A062402, A095956.

Sequence in context: A081479 A335313 A318751 * A256236 A070294 A245568

Adjacent sequences: A096993 A096994 A096995 * A096997 A096998 A096999

Keyword

nonn,hard,more

Author

Labos Elemer, Jul 19 2004

Status

approved