OFFSET
0,2
COMMENTS
For large n, these numbers can be closely approximated by the number of primes < (3^n)^2. For example, the sum of primes < 3^12 = 11150031169. The number of primes < (3^12)^2 = 3^24 = 11152818693. The error here 0.000250.
The second term, 5, is the addition of the primes 2 and 3 since we defined the sequence as less than or equal.
LINKS
Amiram Eldar, Table of n, a(n) for n = 0..43 (calculated using Kim Walisch's primesum program)
Cino Hilliard, Sum of Primes. [broken link]
Cino Hilliard, Sumprimesgmp program. [broken link]
Kim Walisch, Sum of the primes below x (primesum).
FORMULA
PROG
(PARI) a(n) = vecsum(primes([1, 3^n])); \\ Michel Marcus, Jul 02 2024
CROSSREFS
KEYWORD
nonn
AUTHOR
Cino Hilliard, Jun 09 2008
EXTENSIONS
Duplicated term removed and a(20)-a(22) added by Amiram Eldar, Jul 02 2024
STATUS
approved