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%I #8 Feb 19 2016 16:54:53
%S 1,2,3,4,5,13,15,17,19,12,13,29,31,19,62,65,68,145,151,83,30,71,73,38,
%T 39,91,93,50,51,107,109,111,355,203,1036,2117,2147,1216,427,879,889,
%U 462,467,989,3017,1681,1696,3437,3467,1771,1856,3907,3937
%N Numerator of Sum_{k<=n} P(k)/p(k), where p(k) (resp. P(k)) is smallest (resp. largest) prime divisor of k.
%D Handbook of Number Theory, D. S. Mitrinovic et al., Kluwer, Section IV.1(2).
%e Sequence begins 1, 2, 3, 4, 5, 13/2, 15/2, 17/2, 19/2, 12, 13, 29/2, ...
%o (PARI) a(n) = numerator(sum(k=1, n, f = factor(k)[,1]; if (#f, vecmax(f)/vecmin(f), 1))); \\ _Michel Marcus_, Feb 19 2016
%Y Cf. A057155, A020639, A006530.
%K nonn,frac,easy
%O 1,2
%A _N. J. A. Sloane_, Sep 13 2000
%E Name corrected by _Michel Marcus_, Feb 19 2016
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