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%I #14 Aug 07 2012 10:56:11
%S 1,3,1,5,2,1,3,4,9,1,11,5,3,8,15,2,1,17,10,3,5,9,2,21,1,3,14,11,1,6,5,
%T 16,27,3,29,4,8,9,15,20,5,1,35,2,17,4,11,3,39,5,12,41,26,9,3,6,21,28,
%U 45,14,1,5,8,3,15,11,4,51,1,9,34,5,17,18,27,10
%N The difference between the largest and smallest prime factor of n as n runs through the numbers with at least two distinct prime factors.
%C a(n) = A100576(n) if A168638(n) contains only two prime distinct divisors.
%C Nonzero entries of A046665 in the order of appearance. _R. J. Mathar_, Aug 07 2012
%H Michel Lagneau, <a href="/A212332/b212332.txt">Table of n, a(n) for n = 1..10000</a>
%e a(13) = 3 because A168638(13) = 30 = 2*3*5 and 5-2 = 3.
%p for n from 2 to 200 do
%p gpf := A006530(n) ;
%p spf := A020639(n) ;
%p if gpf <> spf then
%p printf("%d,",gpf-spf) ;
%p end if;
%p end do: # _R. J. Mathar_, Aug 07 2012
%Y Cf. A100576, A168638.
%K nonn
%O 1,2
%A _Michel Lagneau_, Aug 07 2012
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