A087559 - OEIS

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A087559

Rearrangement of natural numbers such that n*a(n) + 1 is a prime.

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

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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

Index entries for sequences that are permutations of the natural numbers

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