A358693 Numbers k such that k / (sum of digits of k) is the square of a prime.

12, 24, 36, 48, 81, 150, 225, 375, 441, 735, 882, 1014, 1452, 1521, 1815, 2023, 2028, 2178, 2312, 2535, 2601, 3549, 3610, 4046, 4332, 4335, 4624, 4913, 5054, 5415, 5491, 5780, 6069, 6137, 6358, 6647, 6936, 7581, 7942, 8664, 8959, 9386, 9522, 9747, 10092, 11532, 12321, 12615, 12696

Offset: 1

Author

Andi Fugard, Jan 01 2023

Keywords

• nonn
• base

Comments

Terms k from A001102 such that k / (sum of digits of k) is the square of a prime.

Crossrefs

Cf. A001102, A001248, A007953.

Programs

Mathematica

Select[Range[13000], PrimeQ[Sqrt[#/Plus @@ IntegerDigits[#]]] &] (* Amiram Eldar, Jan 01 2023 *)

PARI

isok(k) = my(r); issquare(k/sumdigits(k), &r) && (denominator(r)==1) && isprime(r); \\ Michel Marcus, Jan 01 2023

Extensions

More terms from Michel Marcus, Jan 01 2023