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 A137257 A number n is included if there is at least one (nonzero) exponent in the prime factorization of n that is not coprime to n. 1

%I

%S 4,12,16,18,20,24,27,28,36,44,48,50,52,54,60,64,68,72,76,80,84,90,92,

%T 98,100,108,112,116,120,124,126,132,135,140,144,148,150,156,160,162,

%U 164,168,172,176,180,188,189,192,196,198,200,204,208,212,216,220,228,234

%N A number n is included if there is at least one (nonzero) exponent in the prime factorization of n that is not coprime to n.

%e 48 = 2^4 * 3^1; so the exponents in the prime-factorization of 48 are 4 and 1. 48 is not coprime to 4; therefore 48 is included in this sequence.

%t Select[Range[3000], GCD[ #, Product[FactorInteger[ # ][[i, 2]], {i, 1, Length[FactorInteger[ # ]]}]] > 1 &] (* _Stefan Steinerberger_, Mar 16 2008 *)

%K nonn

%O 1,1

%A _Leroy Quet_, Mar 11 2008

%E More terms from _Stefan Steinerberger_, Mar 16 2008

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Last modified September 23 16:41 EDT 2020. Contains 337315 sequences. (Running on oeis4.)