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

Author

Labos Elemer, Jul 19 2004

Keywords

• nonn
• hard
• more

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

Examples

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

Crossrefs

Cf. A062402, A095956.