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%I #8 Dec 06 2019 21:42:04
%S 1,1,2,4,1,6,1,6,5,10,1,16,1,6,5,12,1,2,1,20,12,10,1,28,25,4,25,36,1,
%T 20,1,28,25,6,5,40,1,30,5,20,1,36,1,36,5,26,1,12,8,50,53,16,1,22,45,
%U 52,5,16,1,40,1,32,69,12,65,58,1,52,22,40,1,28,1,24,50,44,59,38,1,60,65,70,1
%N Least k such that the concatenation a(1), a(2), a(3), ..., a(n-1), a(n) is divisible by n if and only if n is not a prime.
%C Contribution from _Hagen von Eitzen_, Oct 03 2009: (Start)
%C a(n) < n + 10^floor(log_2(n)).
%C If k >= 1 and n in {10^k, 2*10^k, 5*10^k} then a(n) = n.
%C If n is prime then a(n) in {1, 2}. (End)
%e 3 does not divide 112 while 4 divides 1124.
%K base,nonn,uned
%O 1,3
%A _Amarnath Murthy_, Jun 17 2004
%E More terms from _Hagen von Eitzen_, Oct 03 2009
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