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A134335 Numbers such that the arithmetic mean of their prime factors (counted with multiplicity) is integer, but not prime. 2

%I #8 Aug 02 2022 17:28:17

%S 15,35,39,42,50,51,55,65,77,78,87,91,92,95,110,111,114,115,119,123,

%T 140,141,143,155,159,161,164,170,183,185,186,187,189,201,203,204,209,

%U 215,219,221,222,225,230,235,236,242,247,258,259,264,267,284,285,287,290

%N Numbers such that the arithmetic mean of their prime factors (counted with multiplicity) is integer, but not prime.

%H Hieronymus Fischer, <a href="/A134335/b134335.txt">Table of n, a(n) for n = 1..10000</a>

%e a(1) = 15, since 15 = 3*5 and (3+5)/2 = 4 is not prime.

%e a(5) = 50, since 50 = 2*5*5 and (2+5+5)/3 = 4 is not prime.

%Y Cf. A000040, A001222, A100118, A046363, A133620, A133621.

%Y Cf. A133880, A133890, A133900, A133910, A133911, A046346, A134331, A134332, A134333, A134334.

%K nonn

%O 1,1

%A _Hieronymus Fischer_, Oct 23 2007

%E Definition clarified by the author, May 06 2013

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Last modified September 2 05:36 EDT 2024. Contains 375604 sequences. (Running on oeis4.)