A348623 - OEIS

%I #24 Dec 14 2021 01:43:46

%S 1,2,3,5,7,9,12,14,16,17,19,21,25,28,30,34,36,39,43,45,51,55,59,61,63,

%T 69,73,75,81,86,88,90,96,98,101,103,105,113,115,119,123,127,129,133,

%U 137,139,141,145,149,151,153,159,163,165,173,175,181,183,187,191,193,195,203

%N a(1) = 1; for n > 1 a(n) = a(n-1) + A001227(a(n-1)).

%t NestList[# + Count[Divisors[#], _?OddQ] &, 1, 62] (* _Michael De Vlieger_, Oct 25 2021 *)

%o (PARI) f(n) = sumdiv(n, d, d%2); \\ A001227

%o a(n) = if (n==1, 1, my(x=a(n-1)); x + f(x)); \\ _Michel Marcus_, Oct 26 2021

%o (Python)

%o from math import prod

%o from itertools import islice

%o from sympy import factorint

%o def A348623gen(): # generator of terms

%o     n = 1

%o     yield n

%o     while True:

%o         n += prod(q+1 for p, q in factorint(n).items() if p > 2)

%o         yield n

%o A348623_list = list(islice(A348623gen(),20)) # _Chai Wah Wu_, Dec 13 2021

%Y Cf. A001227, A064491.

%K nonn

%O 1,2

%A _Patryk Kisieniowski_, Oct 25 2021