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A263984
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Least composite primitive root of n-th prime.
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1
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9, 8, 8, 10, 6, 6, 6, 10, 10, 8, 12, 15, 6, 12, 10, 8, 6, 6, 12, 21, 14, 6, 6, 6, 10, 8, 6, 6, 6, 6, 6, 6, 6, 12, 8, 6, 6, 12, 10, 8, 6, 10, 21, 10, 8, 6, 22, 6, 6, 6, 6, 14, 14, 6, 6, 10, 8, 6, 6, 12, 12, 8, 14, 22, 10, 8, 28, 10, 6, 18
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OFFSET
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1,1
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COMMENTS
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The only square in the sequence is a(1) = 9.
It seems nearly certain that all nonsquare composite numbers occur in this sequence.
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LINKS
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MATHEMATICA
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primrootQ[n_, r_] := MultiplicativeOrder[r, n] == EulerPhi[n];
a[n_] := Module[{p = Prime[n], k = 6}, While[PrimeQ[k] || GCD[k, p] != 1 || !primrootQ[p, k], k++]; k];
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PROG
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(PARI) isprimroot(n, r)=znorder(Mod(r, n))==eulerphi(n)
a(n)=my(p=prime(n), k=6); while(isprime(k)||gcd(k, p)!=1||!isprimroot(p, k), k++); k
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CROSSREFS
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KEYWORD
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nonn
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AUTHOR
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STATUS
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approved
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