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Numbers not representable as p+g, where p is a prime and g is a primitive root of p.
3

%I #10 Oct 09 2021 04:42:37

%S 1,2,4,6,9,11,14,16,25,26,35,36,41,45,49,51,64,81,100,121,144,169,196,

%T 225,256,289,324,361,400,441,484,529,576,625,676,729,784,841,900,961,

%U 1024,1089,1156,1225,1296,1369,1444,1521,1600,1681,1764,1849,1936,2025

%N Numbers not representable as p+g, where p is a prime and g is a primitive root of p.

%C This sequence appears to contain all the positive squares (A000290) and a few other numbers (A138327).

%H Amiram Eldar, <a href="/A138326/b138326.txt">Table of n, a(n) for n = 1..375</a>

%t seq[m_] := Module[{p = Select[Range[m], PrimeQ]}, Complement[Range[m], p + PrimitiveRootList[p] // Flatten]]; seq[2000] (* _Amiram Eldar_, Oct 09 2021 *)

%Y Cf. A000290, A060749 (primitive roots), A138327.

%K nonn

%O 1,2

%A _T. D. Noe_, Mar 14 2008