login
A092680
Numbers of the form 3*2^k with a single anti-divisor.
2
3, 6, 96, 393216
OFFSET
1,1
COMMENTS
See A066272 for definition of anti-divisor.
If it exists, a(5) > 3*2^(1000). See A092679. - J.W.L. (Jan) Eerland, Nov 13 2022
FORMULA
a(n) = 3*2^A092679(n).
PROG
(Python)
from itertools import count, islice
from sympy.ntheory.factor_ import antidivisor_count
def A092680_gen(): return filter(lambda n: antidivisor_count(n)==1, (3*2**k for k in count(0)))
A092680_list = list(islice(A092680_gen(), 4)) # Chai Wah Wu, Jan 04 2022
CROSSREFS
KEYWORD
nonn,hard,more
AUTHOR
Lior Manor, Mar 03 2004
STATUS
approved