OFFSET
1,2
COMMENTS
Numbers k that generate the terms in A263299.
a(13) > 10000 if it exists. - Chai Wah Wu, Oct 22 2015
PROG
(Python)
from gmpy2 import is_prime
A261459_list = [k for k in range(10**3) if is_prime(int('1'*k+str(k*(k+1)+1)+'1'*k))]
(PARI) for(n=1, 1e3, if(isprime(eval(Str((10^n - 1)/9, n^2 + n + 1, (10^n - 1)/9))), print1(n", "))); \\ Altug Alkan, Oct 20 2015
CROSSREFS
KEYWORD
nonn,base,more
AUTHOR
Chai Wah Wu, Oct 19 2015
EXTENSIONS
a(13)-a(14) from Michael S. Branicky, Jun 06 2023
STATUS
approved