A333264 Least number k that reaches 1 after n iterations of A206369.

1, 2, 3, 4, 5, 8, 15, 17, 69, 121, 137, 467, 985, 1949, 4049, 8117, 14641, 36383, 62501, 125003, 250007, 958081, 1817513, 3325981, 8062091, 21233813, 42467627, 125828819, 343955189

Offset: 0

Author

Amiram Eldar, Mar 13 2020

Keywords

• nonn
• more

Comments

Least number k such that A330786(k) = n.

Examples

			a(5) = 8 since 8 is the least number that reaches 1 after 5 iterations of A206369: 8 -> 5 -> 4 -> 3 -> 2 -> 1.
		

Crossrefs

Cf. A206369, A330786.

Programs

Mathematica

f[p_, e_] := Sum[(-1)^(e-k)*p^k, {k, 0, e}]; s[1] = 1; s[n_] := Times @@ (f @@@ FactorInteger[n]); numiter[n_] := Length @ FixedPointList[s, n] - 2; n = 0; seq={}; Do[If[numiter[k] == n, AppendTo[seq, k]; n++], {k, 1, 1000}]; seq