A249125 Composite numbers which are a multiple of the concatenation of their prime factors A084317.

4, 8, 9, 16, 25, 27, 32, 49, 50, 64, 81, 100, 121, 125, 128, 169, 200, 243, 250, 256, 289, 343, 361, 400, 500, 512, 529, 625, 729, 800, 841, 961, 1000, 1024, 1250, 1331, 1369, 1600, 1681, 1849, 2000, 2048, 2187, 2197, 2209, 2401, 2500, 2809, 3125, 3200, 3481, 3721, 4000, 4096, 4489, 4913, 5000, 5041, 5329, 6241, 6250, 6400

Offset: 1

Author

M. F. Hasler, Oct 21 2014

Keywords

• nonn
• base

Comments

Prime numbers are excluded since they trivially satisfy the condition.

Multiplicity of the prime factors is ignored.

Among the first 10000 terms, the 182 which are not prime powers are of the form 2^h * 5^k. - Giovanni Resta, May 29 2017

Links

• Giovanni Resta, Table of n, a(n) for n = 1..10000

Crossrefs

Cf. A084317, A069872, A224930, A240265.

Programs

Mathematica

Select[Range[6400], CompositeQ[#] &&  Mod[#, FromDigits@ Flatten[ IntegerDigits /@ First /@ FactorInteger@#]] == 0 &] (* Giovanni Resta, May 29 2017 *)

PARI

for(n=2,9999,isprime(n)||n%A084317(n)||print1(n","))