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 A070007 #10 Mar 28 2015 22:36:23
%S A070007 15,42,45,65,75,77,84,87,126,135,141,168,225,247,252,258,261,285,294,
%T A070007 301,325,335,336,357,375,378,405,410,423,429,481,504,516,539,588,589,
%U A070007 591,618,671,672,675,717,756,767,774,783,785,820,845,847,855,882,986
%N A070007 Arithmetic mean of distinct primes dividing n is a square number.
%C A070007 Subset of A078174. [_R. J. Mathar_, Sep 20 2008]
%H A070007 Michael De Vlieger, <a href="/A070007/b070007.txt">Table of n, a(n) for n = 1..10000</a>
%e A070007 n=1972=2*17*29: mean=(2+17+29)/3=48/3=16, a square.
%t A070007 Select[Range[2, 1000], IntegerQ@ Sqrt[Total[First /@ FactorInteger@ #]/PrimeNu@ #] &] (* _Michael De Vlieger_, Mar 28 2015 *)
%o A070007 (PARI) lista(nn) = {for (n=2, nn, f = factor(n); if ((#f~ != 1) && (type(q=sum(k=1, #f~, f[k,1])/#f~) == "t_INT") && issquare(q), print1(n, ", ")););} \\ _Michel Marcus_, Mar 28 2015
%Y A070007 Cf. A070005, A070006, A001414, A008472.
%K A070007 nonn
%O A070007 1,1
%A A070007 _Labos Elemer_, Apr 11 2002