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 A064579 Inverse permutation to A054082. 2

%I

%S 2,1,4,3,6,8,5,10,7,12,14,9,16,18,11,20,13,22,24,15,26,17,28,30,19,32,

%T 34,21,36,23,38,40,25,42,44,27,46,29,48,50,31,52,33,54,56,35,58,60,37,

%U 62,39,64,66,41,68,43,70,72,45,74,76,47,78,49,80,82,51,84,86,53,88,55

%N Inverse permutation to A054082.

%H <a href="/index/Per#IntegerPermutation">Index entries for sequences that are permutations of the natural numbers</a>

%p A054082 := proc(nmax) local a,k,n,p ; a := [2,1] ; while nops(a) < nmax do n := nops(a)+1 : k := floor((n+1)/2) ; p := 1; while p in a do p := p+1 ; od ; if n mod 2 = 1 then a := [op(a), p+k-1] ; else a := [op(a), p] ; fi ; od ; RETURN(a) ; end: A064579 := proc(a054082) local a,n,ainv ; n := 1; a := [] ; while member(n,a054082,'ainv') do a := [op(a),ainv] ; n := n+1; od; RETURN(a) ; end: a054082 := A054082(200) : a064579 := A064579(a054082) : print(op(a064579)) ; # _R. J. Mathar_, Jun 27 2007

%t a[n_] := If[OddQ[n], Floor[((n+1)/2 - 1) GoldenRatio] + (n+1)/2 + 1, Floor[(n/2 - 1) GoldenRatio] + 2]; a[2] = 1;

%t Sort[Array[{a[#], #}&, 100]][[All, 2]] (* _Jean-François Alcover_, Apr 01 2020 *)

%K nonn,easy

%O 1,1

%A _N. J. A. Sloane_, Oct 16 2001

%E Corrected and extended by _R. J. Mathar_, Jun 27 2007

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Last modified April 20 03:02 EDT 2021. Contains 343121 sequences. (Running on oeis4.)