A361628 Sphenic numbers (products of 3 distinct primes) whose digits are primes.

222, 255, 273, 322, 357, 555, 777, 2222, 2233, 2235, 2255, 2337, 2355, 2373, 2522, 2553, 2555, 2737, 2755, 3237, 3322, 3333, 3335, 3355, 3522, 3535, 3553, 3723, 5222, 5235, 5253, 5322, 5335, 5522, 5523, 5555, 5727, 5735, 5757, 7222, 7257, 7322, 7337, 7527, 7535, 7553, 7557

Offset: 1

Author

Massimo Kofler, Mar 18 2023

Keywords

• nonn
• base

Crossrefs

Intersection of A046034 and A007304.

Cf. A102782.

Programs

Mathematica

Select[Flatten@ Table[FromDigits /@ Tuples[Prime[Range[4]], n], {n, 3, 4}], FactorInteger[#][[;; , 2]] == {1, 1, 1} &] (* Amiram Eldar, Mar 18 2023 *)

PARI

isok(k) = (omega(k)==3) && (bigomega(k)==3) && !#select(x->!isprime(x), digits(k)); \\ Michel Marcus, Mar 21 2023