OFFSET
1,1
EXAMPLE
a(1) = 3 since 13_1 is prime;
a(2) = 13 since 135791113_1197531 is prime;
a(3) = 19 since 135791113151719_1715131197531 is prime.
PROG
(Python)
import sympy
n=1
while n>0:
....s=str(n)
....for m in range(n-2, 0, -2):
........s=str(m)+s+str(m)
....p=int(s)
....if sympy.isprime(p)==True:
........print(n)
....n=n+2
CROSSREFS
KEYWORD
nonn,more,base
AUTHOR
Abhiram R Devesh, Jul 31 2015
STATUS
approved