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 A219095 Numbers k such that if b/c > 1 is the least reduced fraction using divisors b and c of k, then c > 1. 4

%I

%S 6,12,15,18,20,21,24,28,30,35,36,40,42,45,48,54,55,56,60,63,65,66,70,

%T 72,75,77,78,80,84,85,88,90,91,95,96,99,100,102,104,105,108,110,112,

%U 114,115,117,119,120,126,130,132,133,135,138,140,143,144,147,150

%N Numbers k such that if b/c > 1 is the least reduced fraction using divisors b and c of k, then c > 1.

%H Clark Kimberling, <a href="/A219095/b219095.txt">Table of n, a(n) for n = 2..5066</a>

%e For n = 2,...,12, the fractions are 2/1, 3/1, 2/1, 5/1, 3/2, 7/1, 2/1, 3/1, 2/1, 11/1, 4/3, so that

%e A218993 = (2, 3, 2, 5, 3, 7, 2, 3, 2, 11, 4, ... );

%e A219093 = (1, 1, 1, 1, 2, 1, 1, 1, 1, 1, 3, ... );

%e A219094 = (1, 1, 2, 1, 1, 1, 4, 3, 5, 1, 1, ... );

%e A219095 = (6, 12, 15, 18, 20, 21, 24, 28, 30, 35, 36, ... ).

%e The least k for which A219093(k) > 1 is 6, so that a(2) = 6; the next such k is 12, so that a(3) = 12, etc.

%t (See A218993.)

%Y Cf. A218993, A219093, A219095.

%K nonn,easy

%O 2,1

%A _Clark Kimberling_, Feb 06 2013

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Last modified July 31 06:15 EDT 2021. Contains 346369 sequences. (Running on oeis4.)