For n>=2, a(n) = sum{k=1 to n} (smallest prime dividing (n*k)). a(1)=0. 0, 4, 8, 8, 17, 12, 28, 16, 23, 20, 50, 24, 67, 28, 38, 32, 95, 36, 118, 40, 53, 44, 152
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