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

0,2

Comments

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

Links

Table of n, a(n) for n=0..28.

Example

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

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

Crossrefs

Cf. A206369, A330786.

Sequence in context: A108014 A075721 A112479 * A247461 A281303 A264011

Adjacent sequences: A333261 A333262 A333263 * A333265 A333266 A333267

Keyword

nonn,more

Author

Amiram Eldar, Mar 13 2020

Status

approved