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An integer k, k>=2, is in the sequence if A001222(k) (the sum of the exponents in the prime factorization of k) divides A008472(k) (the sum of the distinct primes dividing k).
1

%I #15 Mar 28 2021 07:03:31

%S 2,3,4,5,7,11,13,15,17,19,21,23,27,28,29,31,33,35,37,39,41,42,43,47,

%T 48,51,52,53,55,57,59,61,65,67,69,71,72,73,76,77,78,79,83,84,85,87,89,

%U 91,93,95,97,98,101,103,105,107,108,109,110,111,113,114,115,119,120,123

%N An integer k, k>=2, is in the sequence if A001222(k) (the sum of the exponents in the prime factorization of k) divides A008472(k) (the sum of the distinct primes dividing k).

%H Amiram Eldar, <a href="/A139316/b139316.txt">Table of n, a(n) for n = 1..10000</a>

%e 28 has the prime factorization 2^2 * 7^1. The sum of the exponents, 2+1 = 3, divides the sum of the distinct prime divisors, 2+7 = 9. So 28 is in the sequence.

%t seddpQ[n_]:=Module[{fi=Transpose[FactorInteger[n]]},Divisible[Total[ fi[[1]]],Total[ fi[[2]]]]]; Select[Range[2,150],seddpQ] (* _Harvey P. Dale_, Apr 13 2015 *)

%Y Cf. A001222, A008472.

%K nonn

%O 1,1

%A _Leroy Quet_, Jun 07 2008

%E More terms from _D. S. McNeil_, Mar 23 2009

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Last modified September 20 03:04 EDT 2024. Contains 376016 sequences. (Running on oeis4.)