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

1,1

Links

Mia Boudreau, Table of n, a(n) for n = 1..5000

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

Mathematica

Select[Range[1, 6000, 2], CompositeQ[#] && AllTrue[IntegerDigits[#], MemberQ[{3, 5, 7}, #1] &] &] (* Amiram Eldar, Jun 30 2025 *)

Prog

(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

Crossrefs

Subsequence of A061371.

Subsequence of A320062.

Cf. A061372, A087363.

Sequence in context: A144425 A180329 A367782 * A356765 A020260 A345500

Adjacent sequences: A385474 A385475 A385476 * A385478 A385479 A385480

Keyword

nonn,base

Author

Enrique Navarrete, Jun 30 2025

Status

approved