|
%I #7 Mar 14 2020 04:43:15
%S 1,2,3,4,5,7,9,13,17,19,29,37,49,72,73,103,155,193,277,441,527,769,
%T 1109,1597,2309,2477,4733,6467,8649,12197,16129,23813,36151,48841,
%U 74609,106291,146689,224717,312451,405001,615449,777137,1242487,1540711,2465129,3401341
%N Least number k that reaches 1 after n iterations of A071324.
%C Least number k such that A333262(k) = n.
%H Amiram Eldar, <a href="/A333265/b333265.txt">Table of n, a(n) for n = 0..55</a>
%F a(5) = 7 since 7 is the least number that reaches 1 after 5 iterations of A071324: 7 -> 6 -> 4 -> 3 -> 2 -> 1.
%t 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
%Y Cf. A071324, A333262.
%K nonn
%O 0,2
%A _Amiram Eldar_, Mar 13 2020
|
