A020462 Primes that contain digits 3 and 5 only.

3, 5, 53, 353, 3533, 5333, 33353, 33533, 35353, 35533, 53353, 55333, 333533, 353333, 533353, 535333, 3335533, 3353333, 3353533, 3355553, 3533533, 3553553, 3555353, 5333353, 5333533, 5353553, 5533553, 33335333, 33555553, 35535553, 35553533, 53355353, 53533553

Offset: 1

Author

David W. Wilson

Keywords

• nonn
• base

Links

• Jason Bard, Table of n, a(n) for n = 1..10000 (first 1000 terms from Vincenzo Librandi)

Crossrefs

Subsequence of A030096.

Programs

Maple

sort(convert(`union`(seq(select(isprime,map(t -> 3*(10^d-1)/9 + 2*add(10^(s-1),s=t),combinat:-powerset(d))),d=0..10)),list)); # Robert Israel, Jul 21 2015

Mathematica

Flatten[Table[Select[FromDigits/@Tuples[{3,5},n],PrimeQ],{n,8}]] (* Vincenzo Librandi, Jul 27 2012 *)

Python

from gmpy2 import is_prime, mpz
from itertools import product
A020462_list = [int(''.join(x)) for n in range(1,10) for x in product('35',repeat=n) if is_prime(mpz(''.join(x)))] # Chai Wah Wu, Jul 21 2015