A355606 - OEIS

%I #8 Jul 09 2022 11:07:02

%S 1,2,4,9,14,25,37,57,99,133,182,191,404,469,595,640,780,1195,1884,

%T 2407,2808,3010,3217,3444,4245,4383,5773,8703,10069,10731,12640,14470,

%U 17998,18535,22648,23341,24286,27431,33702,37019,45593,53759,56598,57578,76640,96729,99557,106881,125900,144162

%N The indices where A354606(n) = 1.

%C See A354606 for further details.

%o (Python)

%o from sympy import divisor_count

%o from collections import Counter

%o from itertools import count, islice

%o def f(n): return divisor_count(n)

%o def agen():

%o     n, an, fan, inventory = 1, 1, 1, Counter([1])

%o     yield n

%o     for n in count(2):

%o         an = inventory[fan]

%o         fan = f(an)

%o         inventory.update([fan])

%o         if an == 1: yield n

%o print(list(islice(agen(), 50))) # _Michael S. Branicky_, Jul 09 2022

%Y Cf. A354606, A000005.

%K nonn

%O 1,2

%A _Scott R. Shannon_, Jul 09 2022