A240108 Numbers with primitive root 20.

3, 9, 13, 17, 23, 27, 37, 43, 47, 53, 67, 73, 81, 83, 103, 107, 113, 137, 157, 163, 167, 169, 173, 223, 227, 233, 243, 257, 263, 277, 283, 289, 293, 313, 317, 337, 347, 353, 367, 383, 397, 433, 443, 463, 467, 487, 503, 529, 547, 557, 563, 587, 593, 607

Offset: 1

Author

Vincenzo Librandi, Apr 01 2014

Keywords

• nonn

Links

• Vincenzo Librandi, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. numbers with positive primitive root r: A167791 (r=2), A167792 (r=3), A167793 (r=5), A167794 (r=6), A167795 (r=7), A167796 (r=8), A167797 (r=10), A240028 (r=11), A240030 (r=12), A240032 (r=13), A240094 (r=14), A240096 (r=15), A240100 (r=17), A240103 (r=18), A240106 (r=19).

Cf. numbers with negative primitive root r: A167798 (r=-2), A167799 (r=-3), A167800 (r=-4), A167801 (r=-5), A167802 (r=-6), A167803 (r=-7), A167804 (r=-8), A167805 (r=-9), A167806 (r=-10), A240029 (r=-11), A240031 (r=-12), A240093 (r=-13), A240095 (r=-14), A240097 (r=-15), A240100 (r=-17), A240102 (r=-18), A240104 (r=-19), A240107 (r=-20).

Programs

Mathematica

pr = 20; Select[Range[2, 700], MultiplicativeOrder[pr, #] == EulerPhi[#] &]
Join[{3,9,13,17},Select[Range[610],MemberQ[PrimitiveRootList[#],20]&]] (* Harvey P. Dale, Jul 17 2025 *)