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%I #12 May 18 2019 17:23:33
%S 0,4,8,8,17,12,28,16,23,20,50,24,67,28,38,32,95,36,118,40,53,44,152,
%T 48,81,52,68,56,201,60,236,64,83,68,112,72,293,76,98,80,345,84,392,88,
%U 113,92,450,96,185,100,128,104,525,108,176,112,143,116,604,120,669,124,158
%N For n >= 2, a(n) = Sum_{k=1..n} (smallest prime dividing (n*k)). a(1)=0.
%H Diana Mecum, <a href="/A141800/b141800.txt">Table of n, a(n) for n = 1..1000</a>
%e For n = 5, the smallest prime dividing 1*5=5 is 5. The smallest prime dividing 2*5=10 is 2. The smallest prime dividing 3*5=15 is 3. The smallest prime dividing 4*5=20 is 2. And the smallest prime dividing 5*5=25 is 5. So a(5) = 5+2+3+2+5 = 17.
%t Table[sum=0;Do[sum=sum+Min[Divisors[k*n][[2]],Divisors[n][[2]]],{k,1,n}];
%t sum,{n,2,1000}]; (* then manually add in a(0) term *) (* _Diana L. Mecum_, Jan 02 2009 *)
%Y Cf. A141801.
%K nonn
%O 1,2
%A _Leroy Quet_, Jul 05 2008
%E a(10)-a(63) from _Diana L. Mecum_, Jan 02 2009
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