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 A100923 a(n) = 1 iff 6*n+1 and 6*n-1 are both prime numbers (0 otherwise). 3
 1, 1, 1, 0, 1, 0, 1, 0, 0, 1, 0, 1, 0, 0, 0, 0, 1, 1, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 1, 0, 1, 1, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 1, 0, 0 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,1 LINKS EXAMPLE a(3) = 1 because 6*3-1=17 and 6*3+1=19 are both prime. a(4) = 0 because 6*4-1=23 is prime and 6*4+1=25 is not prime. a(20) = 0 because 6*20-1=119 and 6*20+1=121 are both not prime. MATHEMATICA Table[If[And[PrimeQ[6*k - 1], PrimeQ[6*k + 1]], 1, 0], {k, 1, 110}] CROSSREFS Cf. A000040, A100924, A100925. Sequence in context: A083187 A080339 A167752 * A050073 A120474 A098370 Adjacent sequences:  A100920 A100921 A100922 * A100924 A100925 A100926 KEYWORD nonn AUTHOR Joseph Biberstine (jrbibers(AT)indiana.edu), Nov 22 2004 STATUS approved

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