A308751 - OEIS

%I #15 Jan 25 2022 16:01:05

%S 2,1,3,2,2,2,1,3,9,16,5,3,2,17,9,24,10,25,22,13,46,7,4,2,47,45,23,16,

%T 16,3,2,17,51,72,26,9,73,111,160,49,46,5,47,72,20,146,63,112,28,113,

%U 174,95,80,63,54,160,46,11,47,72,14,12,73,130,37,131,152,51

%N a(n) = (2 + Sum_{k = 1..n-1} A095258(k)) / A095258(n).

%C Are there infinitely many 1's in this sequence?

%H Rémy Sigrist, <a href="/A308751/b308751.txt">Table of n, a(n) for n = 1..10000</a>

%H Rémy Sigrist, <a href="/A308751/a308751.gp.txt">PARI program for A308751</a>

%e a(3) = (2 + A095258(1) + A095258(2)) / A095258(3) = (2 + 1 + 3) / 2 = 3.

%o (PARI) See Links section.

%o (Python)

%o from itertools import islice

%o from sympy import divisors

%o def A308751_gen(): # generator of terms

%o     bset, s = {1}, 3

%o     yield 2

%o     while True:

%o         for d in divisors(s):

%o             if d not in bset:

%o                 yield s//d

%o                 bset.add(d)

%o                 s += d

%o                 break

%o A308751_list = list(islice(A308751_gen(),30)) # _Chai Wah Wu_, Jan 25 2022

%Y Cf. A095258.

%K nonn,look

%O 1,1

%A _Rémy Sigrist_, Jun 22 2019