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Search: id:A087559
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| A087559 |
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Rearrangement of natural numbers such that n*a(n) + 1 is a prime. |
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+0
3
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| 1, 2, 4, 3, 6, 5, 10, 9, 8, 7, 18, 13, 12, 14, 16, 15, 24, 11, 22, 20, 26, 19, 30, 17, 28, 21, 34, 25, 32, 23, 36, 29, 40, 27, 42, 31, 48, 39, 38, 33, 56, 35, 46, 47, 50, 43, 44, 37, 52, 45, 60, 49, 66, 54, 58, 41, 68, 55, 62, 51, 70, 59, 74, 67, 86, 53, 64, 57, 72, 61, 98, 69
(list; graph; listen)
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OFFSET
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1,2
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COMMENT
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k pertaining to A111296. {A111296(n)-1}/n.
If a(n) = m then a(m) = n.
a(a(n)) = n; a(A131221(n)) = A131221(n). - Reinhard Zumkeller (reinhard.zumkeller(AT)gmail.com), Jun 18 2007
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LINKS
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R. Zumkeller, Table of n, a(n) for n = 1..1000
Index entries for sequences that are permutations of the natural numbers
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MAPLE
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s := {seq(i, i=2..2000)}:a[1] := 1:for n from 2 to 120 do l := sort(convert(s, list)): k := 1: while(not isprime(n*l[k]+1)) do k := k+1: if(k>nops(l)) then print("Overflow"):fi:od: a[n] := l[k]:s := s minus {a[n]}:od:seq(a[l], l=1..120); (from Sascha Kurz)
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MATHEMATICA
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l = {}; Do[k = 1; While[MemberQ[l, k] || !PrimeQ[n*k + 1], k++ ]; AppendTo[l, k], {n, 100}]; l - Ryan Propper (rpropper(AT)stanford.edu), Jun 15 2006
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CROSSREFS
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Cf. A111296.
Adjacent sequences: A087556 A087557 A087558 this_sequence A087560 A087561 A087562
Sequence in context: A132340 A132666 A116533 this_sequence A091850 A143273 A141429
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KEYWORD
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nonn
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AUTHOR
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Amarnath Murthy (amarnath_murthy(AT)yahoo.com), Sep 13 2003
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EXTENSIONS
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More terms from Sascha Kurz (sascha.kurz(AT)uni-bayreuth.de), Sep 22 2003
Edited by njas at the suggestion of Andrew Plewe, Jun 09 2007
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