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

1,1

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

Mathematica

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

Prog

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

Crossrefs

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

Sequence in context: A074310 A264576 A356981 * A171042 A068827 A289755

Adjacent sequences: A070272 A070273 A070274 * A070276 A070277 A070278

Keyword

easy,nonn,base

Author

Benoit Cloitre, May 09 2002

Status

approved