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Search: id:A108245
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| A108245 |
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If n-th prime is 4m-1, then a(n) = 4m+1. If n-th prime is 4m+1, then a(n) = 4m-1. |
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2
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| 5, 3, 9, 13, 11, 15, 21, 25, 27, 33, 35, 39, 45, 49, 51, 61, 59, 69, 73, 71, 81, 85, 87, 95, 99, 105, 109, 107, 111, 129, 133, 135, 141, 147, 153, 155, 165, 169, 171, 181, 179, 193, 191, 195, 201, 213, 225, 229, 227, 231, 241, 239, 253, 255, 265, 267, 273, 275, 279
(list; graph; listen)
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OFFSET
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2,1
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EXAMPLE
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11, the 5th prime, is of the form 4m-1, so a(5) = 4m+1 = 13.
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MAPLE
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a:=proc(n) if ithprime(n) mod 4 = 3 then ithprime(n)+2 else ithprime(n)-2 fi end: seq(a(n), n=2..75); (Deutsch)
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CROSSREFS
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Cf. A107323.
Sequence in context: A019955 A075693 A082454 this_sequence A141620 A049829 A137613
Adjacent sequences: A108242 A108243 A108244 this_sequence A108246 A108247 A108248
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KEYWORD
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nonn
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AUTHOR
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Leroy Quet (qq-quet(AT)mindspring.com), Jun 17 2005
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EXTENSIONS
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More terms from Emeric Deutsch (deutsch(AT)duke.poly.edu), Jun 19 2005
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