cp's OEIS Frontend

A336164 a(1) = 1; if n>1, and gcd(a(n-1), n) > 1 then a(n) = a(n-1)/gcd(a(n-1), n), otherwise a(n) = a(n-1) + n - 1.

%I A336164 #27 Mar 18 2023 18:05:18
%S A336164 1,2,4,1,5,10,16,2,10,1,11,22,34,17,31,46,62,31,49,68,88,4,26,13,37,
%T A336164 62,88,22,50,5,35,66,2,1,35,70,106,53,91,130,170,85,127,170,34,17,63,
%U A336164 21,3,52,102,51,103,156,210,15,5,62,120,2,62,1,63,126,190,95,161,228,76
%N A336164 a(1) = 1; if n>1, and gcd(a(n-1), n) > 1 then a(n) = a(n-1)/gcd(a(n-1), n), otherwise a(n) = a(n-1) + n - 1.
%o A336164 (PARI) a(n) = if (n==1, 1, my(prec=a(n-1)); if (gcd(prec, n) > 1, prec/gcd(prec,n), n-1+prec)); \\ _Michel Marcus_, Jul 13 2020
%o A336164 (Python)
%o A336164 from itertools import count, islice
%o A336164 from math import gcd
%o A336164 def A336164_gen(): # generator of terms
%o A336164     yield (a:=1)
%o A336164     for n in count(2):
%o A336164         yield (a:=a+n-1 if (b:=gcd(a,n)) == 1 else a//b)
%o A336164 A336164_list = list(islice(A336164_gen(),30)) # _Chai Wah Wu_, Mar 18 2023
%Y A336164 Cf. A133058.
%K A336164 nonn
%O A336164 1,2
%A A336164 _Todor Szimeonov_, Jul 10 2020