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Search: id:A138030
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| A138030 |
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Numbers n such that n remains prime through 8 iterations of function f(x) = 2x + 1. |
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+0
1
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OFFSET
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1,1
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MATHEMATICA
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Select[Prime[Range[10^8]], PrimeQ[a1=2*#+1]&&PrimeQ[a2=2*a1+1]&&PrimeQ[a3=2*a2+1]&&PrimeQ[a4=2*a3+1]&&PrimeQ[a5=2*a4+1]&&PrimeQ[a6=2*a5+1]&&PrimeQ[a7=2*a6+1]&&PrimeQ[a8=2*a7+1] &]
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CROSSREFS
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Adjacent sequences: A138027 A138028 A138029 this_sequence A138031 A138032 A138033
Sequence in context: A120316 A118079 A115534 this_sequence A104964 A018787 A003825
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KEYWORD
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nonn,bref
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AUTHOR
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Vladimir Orlovsky (4vladimir(AT)gmail.com), May 01 2008
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