A333265 Least number k that reaches 1 after n iterations of A071324.

1, 2, 3, 4, 5, 7, 9, 13, 17, 19, 29, 37, 49, 72, 73, 103, 155, 193, 277, 441, 527, 769, 1109, 1597, 2309, 2477, 4733, 6467, 8649, 12197, 16129, 23813, 36151, 48841, 74609, 106291, 146689, 224717, 312451, 405001, 615449, 777137, 1242487, 1540711, 2465129, 3401341

Offset: 0

Author

Amiram Eldar, Mar 13 2020

Keywords

• nonn

Comments

Least number k such that A333262(k) = n.

Examples

			a(5) = 7 since 7 is the least number that reaches 1 after 5 iterations of A071324: 7 -> 6 -> 4 -> 3 -> 2 -> 1.
		

Links

• Amiram Eldar, Table of n, a(n) for n = 0..55

Crossrefs

Cf. A071324, A333262.

Programs

Mathematica

s[n_] := Plus @@ (-(d = Divisors[n])*(-1)^(Range[Length[d], 1, -1])); numiter[n_] := Length @ FixedPointList[s, n] - 2; n = 0; seq={}; Do[If[numiter[k] == n, AppendTo[seq, k]; n++], {k, 1, 1000}]; seq