A098551 - OEIS

%I #31 Apr 28 2019 15:22:18

%S 1,2,3,4,9,10,15,6,5,16,22,12,23,8,7,14,30,31,43,18,17,20,51,33,11,25,

%T 19,27,61,39,62,29,24,35,13,37,79,41,21,48,87,44,88,46,26,56,101,52,

%U 40,50,28,54,114,69,34,58,47,63,127,71,132,60,42,65,36,73,142,67,49,80,153

%N Inverse of A098550.

%C Now known to be a permutation of the natural numbers: see the 2015 article by Applegate, Havermann, Selcoe, Shevelev, Sloane, and Zumkeller.

%H Reinhard Zumkeller, <a href="/A098551/b098551.txt">Table of n, a(n) for n = 1..10000</a>

%H David L. Applegate, Hans Havermann, Bob Selcoe, Vladimir Shevelev, N. J. A. Sloane, and Reinhard Zumkeller, <a href="http://arxiv.org/abs/1501.01669">The Yellowstone Permutation</a>, arXiv preprint arXiv:1501.01669 [math.NT], 2015.

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

%F A098553(n) = a(a(n)).

%t f[lst_List] := Block[{k = 4}, While[ GCD[ lst[[-2]], k] == 1 || GCD[ lst[[-1]], k] > 1 || MemberQ[lst, k], k++]; Append[lst, k]]; Table[ Position[ Nest[ f, {1, 2, 3}, 120], n], {n, 71}] // Flatten (* _Robert G. Wilson v_, Nov 21 2014 *)

%o (Haskell)

%o import Data.List (elemIndex); import Data.Maybe (fromJust)

%o a098551 = (+ 1) . fromJust . (`elemIndex` a098550_list)

%o -- _Reinhard Zumkeller_, Nov 21 2014

%Y Cf. A098550, A098553.

%Y Cf. A249943 (partial maxima).

%Y Cf. A098479, A255940.

%K nonn

%O 1,2

%A _Reinhard Zumkeller_, Sep 14 2004