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Search: id:A128945
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| A128945 |
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Numbers n such that the greatest prime < 2^n is a twin prime member. |
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+0
1
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| 2, 3, 4, 5, 6, 10, 12, 16, 20, 149, 150, 476, 594, 788, 1574, 1664, 1691, 6117, 6242
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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A014234(a(n)) is in A001097 (twin primes).
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EXAMPLE
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For n=5, 31 is the greatest prime < 2^5 and is a member of the twin prime pair 29, 31.
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PROGRAM
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(PARI) g(n, b)=for(x=1, n, y=precprime(b^x); if(ispseudoprime(y-2), print1(x", ")))
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CROSSREFS
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Sequence in context: A018779 A018382 A018266 this_sequence A048569 A033085 A006543
Adjacent sequences: A128942 A128943 A128944 this_sequence A128946 A128947 A128948
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KEYWORD
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hard,more,nonn
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AUTHOR
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Cino Hilliard (hillcino368(AT)hotmail.com), Apr 28 2007
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EXTENSIONS
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Edited by and terms a(15)-a(17) from Ray Chandler (rayjchandler(AT)sbcglobal.net), May 12 2007
a(18), a(19) Donovan Johnson (donovan.johnson(AT)yahoo.com), Feb 21 2008
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