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 A134617 #9 Jan 21 2017 12:46:43 %S A134617 15,20,21,28,35,39,44,48,51,52,55,65,69,85,91,92,95,108,112,115,116, %T A134617 129,135,141,145,159,164,172,188,189,205,208,209,215,221,225,235,236, %U A134617 245,249,259,268,272,295,297,299,305,309,315,316,320,325,329,339,341,365 %N A134617 Numbers such that the arithmetic mean of the squares of their prime factors (taken with multiplicity) is a prime. %H A134617 Hieronymus Fischer, <a href="/A134617/b134617.txt">Table of n, a(n) for n = 1..10000</a> %e A134617 a(2)=20, since 20=2*2*5 and (2^2+2^2+5^2)/3=33/3=11. %t A134617 amspQ[n_]:=PrimeQ[Mean[Flatten[Table[#[[1]],#[[2]]]&/@FactorInteger[ n]]^2]]; Select[Range[400],amspQ] (* _Harvey P. Dale_, Jan 21 2017 *) %Y A134617 Cf. A001597, A025475, A134333, A134344, A134376. %Y A134617 Cf. A134600, A134602, A134605, A134608, A134613, A134619, A134621. %K A134617 nonn %O A134617 1,1 %A A134617 _Hieronymus Fischer_, Nov 11 2007 %E A134617 Minor edits by the author, May 06 2013