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A122984 Smallest positive composite number, relatively prime to n, such that a(n)+n is also composite. 2

%I

%S 8,25,22,21,4,49,8,25,16,39,4,65,8,25,34,9,4,77,6,49,4,27,4,25,8,9,8,

%T 27,4,91,4,25,16,15,4,49,8,25,10,9,4,143,6,21,4,9,4,77,6,27,4,25,4,65,

%U 8,9,8,27,4,143,4,15,22,21,4,25,8,9,8,51,4,49,4,21,16,9,4,55,6,39,4,9,4,85

%N Smallest positive composite number, relatively prime to n, such that a(n)+n is also composite.

%C Does not include every composite number; in particular, 12 is not present. If a(n) = 12, gcd(n,12) = 1, but then one of n+4 and n+8 is divisible by 3.

%Y Equals A122985(n) - n. Cf. A096076.

%K easy,nonn

%O 1,1

%A _Franklin T. Adams-Watters_, Sep 22 2006

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Last modified April 22 06:35 EDT 2019. Contains 322329 sequences. (Running on oeis4.)