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A333265 Least number k that reaches 1 after n iterations of A071324. 1
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 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

COMMENTS

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

LINKS

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

FORMULA

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

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

CROSSREFS

Cf. A071324, A333262.

Sequence in context: A240178 A039863 A036802 * A055167 A064628 A188674

Adjacent sequences:  A333262 A333263 A333264 * A333266 A333267 A333268

KEYWORD

nonn

AUTHOR

Amiram Eldar, Mar 13 2020

STATUS

approved

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Last modified September 22 06:53 EDT 2020. Contains 337289 sequences. (Running on oeis4.)