A070275 Numbers k such that the sum of the digits of k equals the sum of the prime divisors of k.

2, 3, 5, 7, 84, 160, 250, 336, 468, 735, 936, 975, 1344, 1375, 1408, 1600, 1694, 1872, 2352, 2401, 2500, 2625, 2808, 3744, 3920, 4116, 4913, 5145, 5616, 6084, 6318, 7296, 7497, 7695, 8424, 8624, 8664, 8704, 9126, 9639, 10240, 12168, 12636, 12675, 14896

Offset: 1

Author

Benoit Cloitre, May 09 2002

Keywords

• easy
• nonn
• base

Comments

If k=10^s*m is a term of the sequence where s > 0 and gcd(m,10)=1, then for each positive integer j, 10^j*m is in the sequence, because the sum of the digits of 10^j*k equals the sum of the digits of k and the sum of the distinct prime factors of 10^j*k equals the sum of the distinct prime factors of k. Also it is obvious that m isn't in the sequence. [Jahangeer Kholdi, Oct 07 2013]

Links

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

Crossrefs

Cf. A008472, A057531, A057532, A050689, A070274, A063737, A067077, A285494.

Programs

Mathematica

Rest[Select[Range[20000],Total[Transpose[FactorInteger[#]][[1]]] == Total[ IntegerDigits[#]] &]] (* Harvey P. Dale, Dec 15 2010 *)

PARI

isok(n) = sumdigits(n) == vecsum(factor(n)[,1]); \\ Michel Marcus, May 27 2018