This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
%I A134335 #15 Apr 05 2025 23:18:08
%S A134335 15,35,39,42,50,51,55,65,77,78,87,91,92,95,110,111,114,115,119,123,
%T A134335 140,141,143,155,159,161,164,170,183,185,186,187,189,201,203,204,209,
%U A134335 215,219,221,222,225,230,235,236,242,247,258,259,264,267,284,285,287,290
%N A134335 Numbers such that the arithmetic mean of their prime factors (counted with multiplicity) is an integer, but not a prime.
%H A134335 Hieronymus Fischer, <a href="/A134335/b134335.txt">Table of n, a(n) for n = 1..10000</a>
%e A134335 a(1) = 15, since 15 = 3*5 and (3+5)/2 = 4 is not prime.
%e A134335 a(5) = 50, since 50 = 2*5*5 and (2+5+5)/3 = 4 is not prime.
%t A134335 fp[{a_,b_}]:=a*b;s={};Do[If[q=Total[fp/@FactorInteger[n]]/Total[Last/@FactorInteger[n]];IntegerQ[q]&&!PrimeQ[q],AppendTo[s,n]],{n,2,290}];s (* _James C. McMahon_, Apr 05 2025 *)
%Y A134335 Cf. A000040, A001222, A100118, A046363, A133620, A133621.
%Y A134335 Cf. A133880, A133890, A133900, A133910, A133911, A046346, A134331, A134332, A134333, A134334.
%K A134335 nonn
%O A134335 1,1
%A A134335 _Hieronymus Fischer_, Oct 23 2007
%E A134335 Definition clarified by the author, May 06 2013