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A060084
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a(n) is the least prime not a primitive root of n-th prime.
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2
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2, 3, 5, 2, 3, 3, 2, 5, 2, 5, 2, 3, 2, 2, 2, 7, 3, 3, 3, 2, 2, 2, 3, 2, 2, 5, 2, 3, 2, 2, 2, 3, 2, 5, 5, 2, 2, 5, 2, 13, 3, 3, 2, 2, 7, 2, 5, 2, 3, 2, 2, 2, 2, 2, 2, 2, 5, 2, 2, 2, 2, 17, 2, 2, 2, 7, 2, 2, 3, 3, 2, 2, 2, 3, 5, 2, 5, 2, 2, 2, 3, 3, 2, 2, 2, 3, 2, 2, 5, 2, 3, 2, 2, 3, 2, 2, 5, 2, 3, 3, 3, 7, 3, 2, 2, 2
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OFFSET
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1,1
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LINKS
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EXAMPLE
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a(8) = 5 because 19 is the 8th prime, primes 2 and 3 are primitive roots of 19, but 5 is not.
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MAPLE
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with(numtheory); for n from 1 to 100 do i := 1; while (i < n) and (primroot(ithprime(i) - 1, ithprime(n)) = ithprime(i)) do i := i+1; od; print( ithprime(i)); od:
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MATHEMATICA
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Flatten[Table[Take[Complement[Prime[Range[25]], PrimitiveRoot[Prime[n]]], 1], {n, 100}]] (* Alonso del Arte, Oct 23 2012 *)
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PROG
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(PARI) a(n)=my(q=prime(n)); forprime(p=2, q-1, if(znorder(Mod(p, q))<q-1, return(p))); q \\ Charles R Greathouse IV, Oct 26 2012
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CROSSREFS
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KEYWORD
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easy,nonn
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AUTHOR
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EXTENSIONS
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STATUS
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approved
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