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Search: id:A106736
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| A106736 |
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Primes of the form r(r(r(r(n)+1)+1)+1)+1, where A141468(n)=r(n)=n-th nonprime. |
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1
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| 2, 23, 37, 67, 71, 101, 103, 109, 127, 137, 139, 151, 157, 179, 191, 197, 199, 211, 227, 233, 239, 241, 257, 263, 271, 277, 281, 283, 311, 331, 347, 353, 359, 367, 373, 379, 389, 401, 419, 431, 443, 457, 461, 467, 499, 503, 509, 521, 523, 541, 547, 557, 563
(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=1, then
r(r(r(r(1)+1)+1)+1)+1=r(r(r(0+1)+1)+1)+1=r(r(r(1)+1)+1)+1=r(r(0+1)+1)+1=r(r(1)+1)+1=r(0+1)+1=r(1)+1=0+1=1
(nonprime).
If n=2, then
r(r(r(r(2)+1)+1)+1)+1=r(r(r(1+1)+1)+1)+1=r(r(r(2)+1)+1)+1=r(r(1+1)+1)+1=r(r(2)+1)+1=r(1+1)+1=r(2)+1=1+1=2=a(1).
If n=3, then
r(r(r(r(3)+1)+1)+1)+1=r(r(r(4+1)+1)+1)+1=r(r(r(5)+1)+1)+1=r(r(8+1)+1)+1=r(r(9)+1)+1=r(14+1)+1=r(15)+1=22+1=23=a(2).
If n=4, then
r(r(r(r(4)+1)+1)+1)+1=r(r(r(6+1)+1)+1)+1=r(r(r(7)+1)+1)+1=r(r(10+1)+1)+1=r(r(11)+1)+1=r(16+1)+1=r(17)+1=25+1=26
(nonprime).
If n=5, then
r(r(r(r(5)+1)+1)+1)+1=r(r(r(8+1)+1)+1)+1=r(r(r(9)+1)+1)+1=r(r(14+1)+1)+1=r(r(15)+1)+1=r(22+1)+1=r(23)+1=33+1=34
(nonprime).
If n=6, then
r(r(r(r(6)+1)+1)+1)+1=r(r(r(9+1)+1)+1)+1=r(r(r(10)+1)+1)+1=r(r(15+1)+1)+1=r(r(16)+1)+1=r(24+1)+1=r(25)+1
35+1=36 (nonprime).
If n=7, then
r(r(r(r(7)+1)+1)+1)+1=r(r(r(10+1)+1)+1)+1=r(r(r(11)+1)+1)+1=r(r(16+1)+1)+1=r(r(17)+1)+1=r(25+1)+1=r(26)+1
36+1=37=a(3).
If n=8, then
r(r(r(r(8)+1)+1)+1)+1=r(r(r(12+1)+1)+1)+1=r(r(r(13)+1)+1)+1=r(r(20+1)+1)+1=r(r(21)+1)+1=r(30+1)+1=r(31)+1=44+1=45
(nonprime).
If n=9, then
r(r(r(r(9)+1)+1)+1)+1=r(r(r(14+1)+1)+1)+1=r(r(r(15)+1)+1)+1=r(r(22+1)+1)+1=r(r(23)+1)+1=r(33+1)+1=r(34)+1
48+1=49 (nonprime).
If n=10, then
r(r(r(r(10)+1)+1)+1)+1=r(r(r(15+1)+1)+1)+1=r(r(r(16)+1)+1)+1=r(r(24+1)+1)+1=r(r(25)+1)+1=r(35+1)+1=r(36)+1
50+1=51(nonprime)
If n=11, then
r(r(r(r(11)+1)+1)+1)+1=r(r(r(16+1)+1)+1)+1=r(r(r(17)+1)+1)+1=r(r(25+1)+1)+1=r(r(26)+1)+1=r(36+1)+1=r(37)+1=51+1=52(nonprime),
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: rep := 4: for n from 1 to 400 do arep := n ; for i from 1 to rep do arep := A141468(arep)+1 ; od: if isprime(arep) then printf("%d, ", arep) ; fi; od: [From R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Sep 05 2008]
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CROSSREFS
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Cf. A000040, A141468.
Sequence in context: A007510 A117242 A144550 this_sequence A045392 A107374 A068835
Adjacent sequences: A106733 A106734 A106735 this_sequence A106737 A106738 A106739
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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), Aug 25 2008
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EXTENSIONS
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97 removed and extended by R. J. Mathar (mathar(AT)strw.leidenuniv.nl), Sep 05 2008
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