A138326 -id:A138326 - cp's OEIS frontend

A138325 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.

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, 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, 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

Offset: 1

T. D. Noe, Mar 14 2008

nonn

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

T. D. Noe, Table of n, a(n) for n=1..1000

Cf. A060749 (primitive roots).

A138327 Nonsquares not representable as p+g, where p is a prime and g is a primitive root of p.

Original entry on oeis.org

2, 6, 11, 14, 26, 35, 41, 45, 51

Offset: 1

T. D. Noe, Mar 14 2008

This is sequence is probably complete.

There are no more terms below 10^5. - Amiram Eldar, Oct 09 2021

Cf. A060749 (primitive roots), A138326.

seq[m_] := Module[{p = Select[Range[m], PrimeQ], s}, s = Complement[Range[m], p + PrimitiveRootList[p] // Flatten]; Select[s, !IntegerQ @ Sqrt[#] &]]; seq[100] (* Amiram Eldar, Oct 09 2021 *)

cp's OEIS Frontend

A138325 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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