OFFSET
1,2
LINKS
Alois P. Heinz, Table of n, a(n) for n = 1..10000
FORMULA
Sum_{n>=1} 1/a(n) = Product_{p prime} (1 + Sum_{k in A002808} 1/p^k) = 1.1028952548... . - Amiram Eldar, Jul 02 2022
EXAMPLE
5184 = 2^6 * 3^4 is a term because all exponents are composite numbers.
1 is a term, because it has no prime factorization, and "the empty set has every property". - N. J. A. Sloane, Aug 25 2024
MATHEMATICA
Join[{1}, Select[Range[250000], AllTrue[FactorInteger[#][[;; , 2]], CompositeQ]&]] (* Harvey P. Dale, Aug 25 2024 *)
CROSSREFS
KEYWORD
nonn
AUTHOR
Alois P. Heinz, Dec 08 2018
STATUS
approved