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A172022
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a(n)=prime(n)+(-1)^n.
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0
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1, 4, 4, 8, 10, 14, 16, 20, 22, 30, 30, 38, 40, 44, 46, 54, 58, 62, 66, 72, 72, 80, 82, 90, 96, 102, 102, 108, 108, 114, 126, 132, 136, 140, 148, 152, 156, 164, 166, 174, 178, 182, 190, 194, 196, 200, 210, 224, 226, 230, 232, 240, 240, 252, 256, 264, 268, 272, 276
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OFFSET
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1,2
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COMMENTS
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1 together with A014687.
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LINKS
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Table of n, a(n) for n=1..59.
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FORMULA
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a(n+1)=A014687(n).
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EXAMPLE
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a(1)=prime(1)+(-1)^1=2-1=1.
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MATHEMATICA
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upto=300; Total/@Partition[Riffle[Prime[Range[PrimePi[upto]]], {-1, 1}], 2] (* From Harvey P. Dale, May 12 2011 *)
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PROG
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(PARI) a(n)=prime(n)+(-1)^n \\ Charles R Greathouse IV, May 12, 2011
(PARI) k=1; forprime(p=2, 300, print1(p+(k*=-1)", ")) \\ Charles R Greathouse IV, May 25, 2011
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CROSSREFS
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Cf. A000040, A014687.
Sequence in context: A046558 A180854 A014687 * A152967 A004024 A086663
Adjacent sequences: A172019 A172020 A172021 * A172023 A172024 A172025
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KEYWORD
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nonn,easy,changed
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AUTHOR
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Juri-Stepan Gerasimov, Jan 22 2010
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EXTENSIONS
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Entries checked by D. S. McNeil, Dec 01 2010
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STATUS
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approved
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