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A084696
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Beginning with 3, primes such that a(2n) = {a(2n-1) +a(2n+1)}/2.
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2
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3, 5, 7, 13, 19, 31, 43, 61, 79, 103, 127, 139, 151, 157, 163, 181, 199, 211, 223, 277, 331, 349, 367, 373, 379, 409, 439, 463, 487, 547, 607, 613, 619, 631, 643, 691, 739, 811, 883, 937, 991, 1021, 1051, 1069, 1087, 1129, 1171, 1201, 1231, 1279, 1327, 1399
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OFFSET
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1,1
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COMMENTS
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For n > 1, a(2n) = smallest prime of the form a(2n-1) + 6k where a(2n-1) + 12k is also a prime and is equal to a(2n+1). The difference of successive terms is 2,2,6,6,12,12,18,18,24,24,12,12,6,6,18,18,...
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LINKS
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MATHEMATICA
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f[l_List] := Block[{p = Last[l], k = 2, t}, While[t = {p + k, p + 2k}; ! And @@ PrimeQ /@ t, k += 2 ]; Join[l, t]]; Nest[f, {3}, 26] (* Ray Chandler, Sep 29 2006 *)
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CROSSREFS
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A122809 gives bisection of first difference/2 of this sequence.
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KEYWORD
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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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