OFFSET
1,1
LINKS
Harvey P. Dale, Table of n, a(n) for n = 1..1000
EXAMPLE
9 is a term because prime(9) = 23 and concatenation of 23 and 9 is prime
MATHEMATICA
Select[Range[1000], PrimeQ[Prime[#]10^IntegerLength[#]+#]&] (* Harvey P. Dale, Apr 09 2022 *)
PROG
(PARI) is(k) = ispseudoprime(eval(Str(prime(k), k))); \\ Jinyuan Wang, Apr 10 2020
(Python)
from sympy import isprime, prime
def aupto(lim):
return [k for k in range(1, lim+1) if isprime(int(str(prime(k))+str(k)))]
print(aupto(837)) # Michael S. Branicky, Mar 09 2021
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Zak Seidov, Jun 29 2003
EXTENSIONS
More terms from Jinyuan Wang, Apr 10 2020
STATUS
approved