OFFSET
1,1
EXAMPLE
191, 71917, 177191717, ... are prime.
PROG
(Python)
from sympy import isprime
def aupton(terms):
alst, astr = [9], "9"
for n in range(2, terms+1):
an = 1
while not isprime(int(str(an) + astr + str(an))): an += 1
alst.append(an); astr = str(an) + astr + str(an)
return alst
print(aupton(60)) # Michael S. Branicky, Sep 01 2021
CROSSREFS
KEYWORD
base,nonn
AUTHOR
Amarnath Murthy, May 23 2003
EXTENSIONS
More terms from Ray Chandler, Aug 03 2003
STATUS
approved