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A227625
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Indicator sequence of primes p > 3: k = p mod 6, if k = 5 then a(n) = -1, if k = 1 then a(n) = 1 else a(n) = 0, a(2) = -1, a(3) = 1.
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1
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0, -1, 1, 0, -1, 0, 1, 0, 0, 0, -1, 0, 1, 0, 0, 0, -1, 0, 1, 0, 0, 0, -1, 0, 0, 0, 0, 0, -1, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, -1, 0, 1, 0, 0, 0, -1, 0, 0, 0, 0, 0, -1, 0, 0, 0, 0, 0, -1, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, -1, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, -1, 0, 0
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OFFSET
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1
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LINKS
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MATHEMATICA
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Join[{0, -1, 1}, Table[If[!PrimeQ[n], 0, If[Mod[n, 6] = 1, 1, -1], {n, 4, 100}]] (* T. D. Noe, Jul 20 2013 *)
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CROSSREFS
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Cf. A129950 (indicator function of twin primes), A010051 (characteristic function of primes: 1 if n is prime else 0).
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KEYWORD
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sign
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AUTHOR
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STATUS
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approved
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