A020462 - OEIS

%I #19 Feb 09 2025 18:49:07

%S 3,5,53,353,3533,5333,33353,33533,35353,35533,53353,55333,333533,

%T 353333,533353,535333,3335533,3353333,3353533,3355553,3533533,3553553,

%U 3555353,5333353,5333533,5353553,5533553,33335333,33555553,35535553,35553533,53355353,53533553

%N Primes that contain digits 3 and 5 only.

%H Vincenzo Librandi, <a href="/A020462/b020462.txt">Table of n, a(n) for n = 1..1000</a>

%p 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

%t Flatten[Table[Select[FromDigits/@Tuples[{3,5},n],PrimeQ],{n,8}]] (* _Vincenzo Librandi_, Jul 27 2012 *)

%o (Python)

%o from gmpy2 import is_prime, mpz

%o from itertools import product

%o 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

%Y Subsequence of A030096.

%K nonn,base

%O 1,1

%A _David W. Wilson_