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Search: id:A144517
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| A144517 |
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Primes of the form: prime(n)-nonprime(n)=nonprime and prime(n)+nonprime(n)=prime. |
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1
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| 7, 23, 31, 41, 101, 109, 227, 241, 311, 347, 389, 587, 701, 757, 859, 947, 977, 1063, 1069, 1123, 1181, 1229, 1237, 1289, 1303, 1327, 1451, 1489, 1543, 1559, 1613, 1669, 1733, 1787, 1879, 2011, 2029, 2039, 2203, 2213, 2281, 2357, 2393, 2459, 2503, 2593
(list; graph; listen)
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OFFSET
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1,1
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EXAMPLE
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If 7(4)-6(4)=1(nonprime) and 7(4)+6(4)=13(prime), then 7=a(1). If 31(11)-16(11)=15(nonprime) and 31(11)+16(11)=47(prime), then 31=a(2). If 41(13)-20(13)=21(nonprime) and 41(13)+20(13)=61(prime), then 41=a(3). If 101(26)-36(20)=65(nonprime) and 101(26)+36(26)=137(prime), then 101=a(4). If 109(29)-40(29)=69(nonprime) and 109(29)+40(29)=149(prime), then 109=a(5), etc.
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MAPLE
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A141468 := proc(n) option remember; local a; if n = 1 then 0; else for a from procname(n-1)+1 do if not isprime(a) then return a; end if; od: end if; end proc: A144517 := proc(n) option remember; local p, i; if n = 1 then 7; else p := nextprime(procname(n-1)) ; while true do i := numtheory[pi](p) ; if not isprime(p-A141468(i)) and isprime(p+A141468(i)) then return p; fi; p := nextprime(p) ; end do: end if; end: seq(A144517(n), n=1..80) ; [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Oct 22 2009]
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CROSSREFS
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Cf. A000040, A141468.
Sequence in context: A078515 A044449 A095087 this_sequence A091531 A036259 A004628
Adjacent sequences: A144514 A144515 A144516 this_sequence A144518 A144519 A144520
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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), Dec 15 2008
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EXTENSIONS
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Roughly 20 percent of the entries corrected by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Oct 22 2009
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