OFFSET
1,2
COMMENTS
No term is a multiple of 3. The decimal expansion of each corresponding prime is n's decimal expansion with n 3's concatenated. Primes and probable primes found by PrimeForm. Primes for 275 and 1556 proved by Primo. No more terms up to 30000.
No more terms up to 50000. - Michael S. Branicky, Oct 11 2024
EXAMPLE
The numbers 1 and 2 are terms because 13 and 233 are prime.
PROG
(PARI) is(n)=ispseudoprime(n*10^n+(10^n-1)/3) \\ Charles R Greathouse IV, Jun 13 2017
CROSSREFS
KEYWORD
more,nonn
AUTHOR
Rick L. Shepherd, Mar 27 2010
EXTENSIONS
a(5) from Michael S. Branicky, Oct 11 2024
STATUS
approved