A385477 Composite numbers whose digits are odd prime numbers.
33, 35, 55, 57, 75, 77, 333, 335, 355, 357, 375, 377, 533, 535, 537, 553, 555, 573, 575, 735, 737, 753, 755, 775, 777, 3333, 3335, 3337, 3353, 3355, 3357, 3375, 3377, 3535, 3537, 3553, 3555, 3573, 3575, 3577, 3735, 3737, 3753, 3755, 3757, 3773, 3775, 3777, 5335, 5337, 5353, 5355, 5357
Offset: 1
Links
- Mia Boudreau, Table of n, a(n) for n = 1..5000
Programs
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Maple
A:=3,5,7: B:= [A]: for d from 2 to 4 do B:= map(f,B); A:= A,op(B) od: remove(isprime,[A]); # Robert Israel, Jun 30 2025
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Mathematica
Select[Range[1, 6000, 2], CompositeQ[#] && AllTrue[IntegerDigits[#], MemberQ[{3, 5, 7}, #1] &] &] (* Amiram Eldar, Jun 30 2025 *) -
Python
from sympy import isprime from itertools import count, islice, product def agen(): yield from (t for d in count(2) for p in product("357", repeat=d) if not isprime(t:=int("".join(p)))) print(list(islice(agen(), 53))) # Michael S. Branicky, Jun 30 2025