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Search: id:A071680
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| A071680 |
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Primes which are the arithmetic mean of their prime predecessor and another prime. |
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+0
3
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| 5, 37, 53, 67, 157, 173, 211, 257, 263, 277, 373, 479, 563, 593, 607, 613, 631, 653, 733, 809, 947, 977, 1009, 1103, 1123, 1187, 1223, 1297, 1367, 1471, 1511, 1607, 1663, 1721, 1747, 1753, 1783, 1867, 1901, 1907, 1931, 1993, 2137, 2287, 2377, 2411, 2417
(list; graph; listen)
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OFFSET
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1,1
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EXAMPLE
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A000040(12)=37, A000040(12-1)=31, 37=(31+43)/2, therefore 37 is a term.
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MATHEMATICA
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p = q = 2; lst = {}; Do[q = Prime@n; If[PrimeQ[2q - p], AppendTo[lst, q]]; p = q, {n, 2, 400}]; lst (* Robert G. Wilson v (rgwv@rgwv.com), Mar 22 2007 *)
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CROSSREFS
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Cf. A071681, A006562 is a subsequence.
Sequence in context: A043075 A106129 A096673 this_sequence A141182 A127589 A031913
Adjacent sequences: A071677 A071678 A071679 this_sequence A071681 A071682 A071683
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KEYWORD
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nonn
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AUTHOR
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Reinhard Zumkeller (reinhard.zumkeller(AT)lhsystems.com), May 31 200; revised Jul 16 2003
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EXTENSIONS
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Thanks to Sven Simon for noticing errors in the original version.
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