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Search: id:A142343
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| A142343 |
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Primes of the form (p(n)+r(n))/5, where p(n)=n-th prime and r(n)=n-th nonprime. |
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+0
1
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| 11, 31, 43, 47, 73, 103, 109, 113, 127, 211, 239, 269, 353, 443, 509, 631, 733, 743, 823, 839, 881, 887, 1051, 1213, 1277, 1283, 1303, 1307, 1321, 1571, 1583, 1597, 1709, 1747, 1783, 1801, 1997, 2003, 2017, 2087, 2111, 2239, 2267, 2441, 2503, 2591, 2609
(list; graph; listen)
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OFFSET
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1,1
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EXAMPLE
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If n=12, then (p(12)+r(12))/5=(37+18)/5=11=a(1).
If n=30, then (p(30)+r(30))/5=(113+42)/5=31=a(2).
If n=38, then (p(38)+r(38))/5=(163+52)/5=43=a(3).
If n=41, then (p(41)+r(41))/5=(179+56)/5=47=a(4).
If n=61, then (p(61)+r(61))/5=(283+82)/5=73=a(5), etc.
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MAPLE
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A141468 := proc(n) option remember ; if n = 1 then 0; else for a from procname(n-1)+1 do if not isprime(a) then RETURN(a) ; fi; od: fi: end: A000040 := proc(n) ithprime(n) ; end: for n from 1 to 3000 do c := A000040(n)+A141468(n) ; if c mod 5 = 0 then if isprime(c/5) then printf("%d, ", c/5) ; fi; fi; od: [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Nov 03 2008]
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CROSSREFS
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Cf. A000040, A141468.
Sequence in context: A138656 A144234 A109548 this_sequence A043124 A043904 A152293
Adjacent sequences: A142340 A142341 A142342 this_sequence A142344 A142345 A142346
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KEYWORD
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nonn
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AUTHOR
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Juri-Stepan Gerasimov (2stepan(AT)rambler.ru), Sep 19 2008
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EXTENSIONS
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97 removed, 137 replaced by 127, 503 replaced by 509 and extended by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Nov 03 2008
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