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 A172490 Primes p of the form 4m+3 for which there are exactly as many primitive roots modulo p in the interval [0,p/2] as in the interval [p/2,p]. 2
 7, 31, 43, 67, 307, 367, 487, 643, 1327, 1663, 2371, 3643, 3847, 4327, 4951, 6091, 6571, 8263, 9151, 9187, 11239, 11383, 11863, 15307, 24007, 24151, 27847, 30091, 30643, 33619, 36871, 42187, 44171, 46279, 46591, 48787, 70843, 71887, 72103, 72379, 73363, 79867, 82003, 92503, 95467, 106243, 110431, 120943, 126031, 130363, 139759, 143827, 162751, 167107, 173191, 174859, 183247 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 COMMENTS Primes 4*k+3 where half of the primitive roots are <= (p-1)/2. The sequence is probably infinite. Primes of the form 4m+1 always have as many primitive roots in [0,p/2] as in [p/2,p] (see A172480). LINKS Table of n, a(n) for n=1..57. MAPLE with(numtheory): p:=3: while p<1000 do if(p mod 4 = 3)then b1:=0: b2:=0: m:=primroot(p): while not m=FAIL do if(m

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Last modified May 29 00:29 EDT 2024. Contains 372921 sequences. (Running on oeis4.)