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A108154
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a(n) = n^2 - n + 1 if prime else 0.
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0
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0, 3, 7, 13, 0, 31, 43, 0, 73, 0, 0, 0, 157, 0, 211, 241, 0, 307, 0, 0, 421, 463, 0, 0, 601, 0, 0, 757, 0, 0, 0, 0, 0, 1123, 0, 0, 0, 0, 1483, 0, 0, 1723, 0, 0, 0, 0, 0, 0, 0, 0, 2551, 0, 0, 0, 2971, 0, 0, 3307, 0, 3541, 0, 0, 3907, 0, 0, 0, 4423, 0, 0, 4831, 0, 5113, 0, 0, 0, 5701, 0
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OFFSET
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1,2
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LINKS
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Table of n, a(n) for n=1..77.
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EXAMPLE
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1^2 - 1 + 1 = 1, which is not prime, so a(1)=0;
2^2 - 2 + 1 = 3, which is prime, so a(2)=3;
3^3 - 3 + 1 = 7, which is prime, so a(3)=7.
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MATHEMATICA
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f[n_] := Block[{p = n^2 - n + 1}, If[ PrimeQ[p], p, 0]]; Table[ f[n], {n, 77}] (* Robert G. Wilson v, Jun 07 2005 *)
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PROG
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(PARI) vector(80, n, if (isprime(p=n^2-n+1), p, 0)) \\ Michel Marcus, Jul 31 2015
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CROSSREFS
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Cf. A002061, A002383, A002384.
Sequence in context: A167490 A081533 A096856 * A010260 A258136 A209387
Adjacent sequences: A108151 A108152 A108153 * A108155 A108156 A108157
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KEYWORD
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easy,nonn
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AUTHOR
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Pierre CAMI, Jun 06 2005
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EXTENSIONS
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More terms from Robert G. Wilson v, Jun 07 2005
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STATUS
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approved
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