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Search: id:A141636
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| A141636 |
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Primes of the form c(c(c(i)-3)-3)-3, where A002808(i)=c(i)=i-th composite. |
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| 7, 11, 13, 17, 19, 31, 37, 43, 59, 61, 79, 83, 97, 109, 137, 149, 151, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229, 233, 251, 269, 293, 307, 313, 317, 337, 347, 349, 353, 373, 379, 383, 397, 419, 421, 431, 433, 443, 457, 461, 463, 467, 487, 491, 503, 509, 541, 547, 557, 563, 569, 571, 577, 587, 593
(list; graph; listen)
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OFFSET
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1,1
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EXAMPLE
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If i=1, then c(c(c(1)-3)-3)-3=c(c(4-3)-3)-3=c(4-3)-3=4-3=1 (nonprime).
If i=2, then c(c(c(2)-3)-3)-3=c(c(6-3)-3)-3=c(8-3)-3=c(5)-3=10-3=7=a(1).
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MAPLE
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A002808 := proc(n) option remember ; if n = 1 then 4; else for a from procname(n-1)+1 do if not isprime(a) then RETURN(a); fi; od: fi; end: rep := 3: for n from 1 to 800 do arep := n ; for i from 1 to rep do arep := A002808(arep)-3 ; od: if isprime(arep) then printf("%d, ", arep) ; fi; od: - Removed erroneous examples. Correctly roughly 10 percent of the values. Added Maple. - R. J. Mathar, Sep 05 2008
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CROSSREFS
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Cf. A002808, A000040.
Sequence in context: A038961 A127903 A141638 this_sequence A098414 A110583 A103486
Adjacent sequences: A141633 A141634 A141635 this_sequence A141637 A141638 A141639
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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 03 2008
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EXTENSIONS
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Removed erroneous examples. Correctly roughly 10 percent of the values. Added Maple. - R. J. Mathar, Sep 05 2008
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