OFFSET
1,2
COMMENTS
If k and m are coprime terms then k*m is also a term.
The least odd term above 1 is a(55) = 945, the least term above 1 that is coprime to 6 is a(378) = 10465, least term above 1 that is coprime to 30 is a(3122) = 151487, and the least term above 1 that is coprime to 210 is a(6858) = 414713.
LINKS
Amiram Eldar, Table of n, a(n) for n = 1..10000
EXAMPLE
2 is a term since A020696(2) = 6 is divisible by 2.
MATHEMATICA
v[n_] := Times @@ (Divisors[n] + 1); Select[Range[1000], Divisible[v[#], #] &]
PROG
(PARI) f(n) = my(d = divisors(n)); prod(i=1, #d, d[i]+1); \\ A020696
isok(k) = !(f(k) % k); \\ Michel Marcus, Jun 30 2022
(Python)
from itertools import count, islice
from functools import reduce
from sympy import divisors
def A355331_gen(startvalue=1): # generator of terms >= startvalue
return filter(lambda n:reduce(lambda a, b:a*b%n, (d+1 for d in divisors(n, generator=True)))%n==0, count(max(startvalue, 1)))
CROSSREFS
KEYWORD
nonn
AUTHOR
Amiram Eldar, Jun 29 2022
STATUS
approved