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A154274
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Primes of the form: nonprime(prime(n))-(-1)^n.
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0
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2, 3, 17, 19, 71, 97, 127, 131, 139, 191, 193, 227, 229, 251, 281, 337, 349, 353, 389, 443, 503, 541, 557, 563, 571, 613, 659, 701, 719, 727, 743, 877, 911, 971, 1031, 1087, 1091, 1103, 1217, 1297, 1301, 1409, 1439, 1451, 1481, 1531, 1549, 1657, 1697, 1741
(list; graph; refs; listen; history; internal format)
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OFFSET
| 1,1
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COMMENTS
| Where n-th "prime nonprime" = A141468(A000040(n))) and 1-th "prime nonprime" = 0.
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EXAMPLE
| If n=1 and nonprime(prime(1))-(-1)^1=nonprime(2)+1=1+1=2(prime), then 2=a(1). If n=2 and nonprime(prime(2))-(-1)^2=nonprime(3)-1=4-1=3(prime), then 3=a(2). If n=3, then nonprime(prime(3))-(-1)^3=nonprime(5)+1=8+1=9(composite). If n=4, then nonprime(prime(4))-(-1)^4=nonprime(7)-1=10-1=9(composite). If n=5 and nonprime(prime(5))-(-1)^5=nonprime(11)+1=16+1=17(prime), then 17=a(3), etc.
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MAPLE
| A141468 := proc(n) if n <= 2 then n-1 ; else for a from procname(n-1)+1 do if not isprime(a) then RETURN(a) ; fi; od; fi: end: for n from 1 to 400 do p := A141468(ithprime(n))-(-1)^n ; if isprime(p) then printf("%d, ", p); fi; od: [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Aug 14 2009]
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CROSSREFS
| Cf. A000040, A141468.
Sequence in context: A178437 A051074 A051094 * A140834 A121409 A041295
Adjacent sequences: A154271 A154272 A154273 * A154275 A154276 A154277
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KEYWORD
| nonn
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AUTHOR
| Juri-Stepan Gerasimov (2stepan(AT)rambler.ru), Jan 06 2009
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EXTENSIONS
| Corrected and extended by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Aug 14 2009
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