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 A087559 Rearrangement of natural numbers such that n*a(n) + 1 is a prime. 3
 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; refs; listen; history; text; internal format)
 OFFSET 1,2 COMMENTS 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, Jun 18 2007 LINKS R. Zumkeller, Table of n, a(n) for n = 1..1000 MAPLE 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); # Sascha Kurz MATHEMATICA l = {}; Do[k = 1; While[MemberQ[l, k] || !PrimeQ[n*k + 1], k++ ]; AppendTo[l, k], {n, 100}]; l (* Ryan Propper, Jun 15 2006 *) CROSSREFS Cf. A111296. Sequence in context: A132340 A132666 A116533 * A193298 A168007 A359114 Adjacent sequences: A087556 A087557 A087558 * A087560 A087561 A087562 KEYWORD nonn AUTHOR Amarnath Murthy, Sep 13 2003 EXTENSIONS More terms from Sascha Kurz, Sep 22 2003 Edited by N. J. A. Sloane at the suggestion of Andrew S. Plewe, Jun 09 2007 STATUS approved

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Last modified February 3 23:01 EST 2023. Contains 360045 sequences. (Running on oeis4.)