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Least prime p such that n = p + g, where g is a primitive root of p, or 0 if there is no such prime p.
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%I #5 Mar 30 2012 17:22:47

%S 0,0,2,0,3,0,5,5,0,7,0,7,11,0,13,0,11,11,11,13,19,17,17,13,0,0,17,17,

%T 17,23,17,19,19,19,0,0,23,23,29,23,0,23,23,23,0,43,29,29,0,29,0,31,31,

%U 37,29,29,37,41,37,41,37,43,41,0,41,47,41,61,37,41,41,37,43,53,41,41,43,47

%N Least prime p such that n = p + g, where g is a primitive root of p, or 0 if there is no such prime p.

%C Sequence A138128 gives the number of representations for each n and sequence A138326 lists the values of n that are not represented.

%H T. D. Noe, <a href="/A138325/b138325.txt">Table of n, a(n) for n=1..1000</a>

%Y Cf. A060749 (primitive roots).

%K nonn

%O 1,3

%A _T. D. Noe_, Mar 14 2008