login
A107689
Primes with digital product = 3.
17
3, 13, 31, 113, 131, 311, 11113, 11131, 11311, 113111, 131111, 311111, 11111131, 11111311, 11113111, 11131111, 111111113, 111111131, 111113111, 131111111, 11111111113, 11111111131, 11113111111, 11131111111, 31111111111
OFFSET
1,1
LINKS
MATHEMATICA
Flatten[ Table[ Select[ Sort[ FromDigits /@ Permutations[ Flatten[{3, Table[1, {n}]}]]], PrimeQ[ # ] &], {n, 0, 12}]]
PROG
(Python)
from sympy import isprime
def agen():
digits = 0
while True:
for i in range(digits+1):
t = int("1"*(digits-i) + "3" + "1"*i)
if isprime(t): yield t
digits += 1
g = agen()
print([next(g) for i in range(25)]) # Michael S. Branicky, Mar 13 2021
KEYWORD
base,nonn
AUTHOR
STATUS
approved