OFFSET
1,2
COMMENTS
It appears that apart from a very small number of exceptions this sequence consists of the numbers that are neither primes nor twice primes (A264828).
The known exceptions (based on the first 20000 terms) are: (a) the three primes A347113(1423) = 1327, A347113(10686) = 9967, and A347113(83051) = 77647 that are unusually close to the line y=x, and (b) the 27 terms [8, 9, 16, 20, 21, 25, 28, 33, 35, 39, 45, 49, 51, 52, 55, 57, 85, 95, 111, 116, 117, 121, 133, 143, 145, 169, 187] which are in A264828 but are not in the present sequence.
This list of 27 exceptions is surprisingly similar to A181780, but this may be just a coincidence.
LINKS
N. J. A. Sloane, Table of n, a(n) for n = 1..20000
CROSSREFS
KEYWORD
nonn
AUTHOR
N. J. A. Sloane, Nov 20 2021
STATUS
approved