OFFSET
1,1
LINKS
MATHEMATICA
Select[10*Range[0, 10^7] + 7, CompositeQ[#] && Divisible[# - 1, CarmichaelLambda[#]] &] (* Amiram Eldar, Jul 24 2022 *)
PROG
(Python)
from itertools import count, islice
from sympy import factorint
def A355307_gen(): # generator of terms
for n in count(7, 10):
f = factorint(n)
if len(f) == sum(f.values()) > 1 and not any((n-1) % (p-1) for p in f):
yield n
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Omar E. Pol, Jul 24 2022
STATUS
approved