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

1,1

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

Mathematica

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

Prog

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

Crossrefs

Cf. A084317, A069872, A224930, A240265.

Sequence in context: A046447 A087244 A080062 * A377819 A306531 A363722

Adjacent sequences: A249122 A249123 A249124 * A249126 A249127 A249128

Keyword

nonn,base

Author

M. F. Hasler, Oct 21 2014

Status

approved