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Search: id:A110359
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| A110359 |
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a(n) = n+1 if n+1 is a prime else a(n) = 2n+1 if 2n+1 is a prime else a(n) = 2*(2n+1) +1 =g(n) if this number is prime else the next candidate is 2* (g(n) +1 etc. |
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+0
1
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| 2, 3, 7, 5, 11, 7, 31, 17, 19, 11, 23, 13, 223, 29, 31, 17, 71, 19, 79, 41, 43, 23, 47, 199, 103, 53, 223, 29, 59, 31, 127, 131, 67, 139, 71, 37, 151, 311, 79, 41, 83, 43, 738197503, 89, 367, 47, 191, 97, 199, 101, 103, 53, 107, 109, 223, 113, 463, 59, 239, 61, 991, 251
(list; graph; listen)
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OFFSET
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1,1
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COMMENT
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Subsidiary sequence: number of steps to reach a prime.
a(73) takes more than 2000 iterations, if it exists. - Joshua Zucker (joshua.zucker(AT)stanfordalumni.org), May 08 2006
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EXAMPLE
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a(13) = 223, 13+1 = 14 is composite, 13*2 +1 = 27 is composite, 27*2 +1 = 55, 55*2 +1 =111 and finally 111*2 +1 = 223 is a prime.
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CROSSREFS
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Sequence in context: A034694 A050921 A087386 this_sequence A092977 A057218 A087387
Adjacent sequences: A110356 A110357 A110358 this_sequence A110360 A110361 A110362
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KEYWORD
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easy,nonn
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AUTHOR
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Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Jul 23 2005
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EXTENSIONS
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More terms from Joshua Zucker (joshua.zucker(AT)stanfordalumni.org), May 08 2006
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