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Search: id:A132992
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| A132992 |
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Twin prime pair averages n such that 3*n and 9*n are also averages of twin prime pairs. |
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| 32970, 180180, 273000, 633570, 879690, 991620, 1189650, 2219490, 3229380, 4111170, 4515630, 7384440, 7392630, 7398930, 7431270, 9022440, 9861390, 12183360, 12307680, 12866280, 14619990, 14717640, 14917560, 15458100
(list; graph; listen)
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OFFSET
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1,1
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LINKS
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K. Brockhaus, Table of n, a(n) for n = 1..384.
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EXAMPLE
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32970, 3*32970 = 98910, 9*32970 = 296730 are averages of twin prime pairs.
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MATHEMATICA
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TwinPrimeAverageQ[n_]:=If[PrimeQ[n-1]&&PrimeQ[n+1], True, False](*TwinPrimeAverageQ*)lst={}; Do[If[TwinPrimeAverageQ[n], If[TwinPrimeAverageQ[3*n], If[TwinPrimeAverageQ[9*n], (*Print[n]; *)AppendTo[lst, n]]]], {n, 7!, 3*10!}]; lst
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PROGRAM
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(MAGMA) [ a: p in PrimesUpTo(16000000) | IsPrime(a+1) and IsPrime(3*a-1) and IsPrime(3*a+1) and IsPrime(9*a-1) and IsPrime(9*a+1) where a is p+1 ]; [From Klaus Brockhaus, Dec 04 2009]
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CROSSREFS
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Cf. A014574 (average of twin prime pairs).
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KEYWORD
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nonn,new
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AUTHOR
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Vladimir Orlovsky (4vladimir(AT)gmail.com), Aug 26 2008
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EXTENSIONS
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Edited and extended by Klaus Brockhaus (klaus-brockhaus(AT)t-online.de), Dec 04 2009
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