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 A319246 #8 Sep 16 2018 21:36:19
%S A319246 0,1,2,3,3,4,4,5,6,5,5,7,8,6,6,9,7,10,6,11,7,8,7,12,9,8,13,7,14,10,15,
%T A319246 9,16,8,10,11,17,18,12,9,8,19,11,8,20,21,13,9,9,22,14,23,10,15,12,24,
%U A319246 10,13,16,11,25,26,10,27,9,17,28,29,9,14,30,11,12
%N A319246 Sum of prime indices of the n-th squarefree number.
%C A319246 A prime index of n is a number m such that prime(m) divides n.
%e A319246 The 19th squarefree number is 30 with prime indices (3,2,1), so a(19) = 6.
%t A319246 Table[Total[Cases[FactorInteger[n],{p_,k_}:>k*PrimePi[p]]],{n,Select[Range[100],SquareFreeQ]}]
%Y A319246 Rows sums of A319247.
%Y A319246 Cf. A000720, A001222, A005117, A056239, A072047, A265668, A299755, A299757, A319241, A319242.
%K A319246 nonn
%O A319246 1,3
%A A319246 _Gus Wiseman_, Sep 15 2018