A098551 Inverse of A098550.

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, 19, 27, 61, 39, 62, 29, 24, 35, 13, 37, 79, 41, 21, 48, 87, 44, 88, 46, 26, 56, 101, 52, 40, 50, 28, 54, 114, 69, 34, 58, 47, 63, 127, 71, 132, 60, 42, 65, 36, 73, 142, 67, 49, 80, 153

Offset: 1

Author

Reinhard Zumkeller, Sep 14 2004

Keywords

• nonn

Comments

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

Links

• Reinhard Zumkeller, Table of n, a(n) for n = 1..10000
• David L. Applegate, Hans Havermann, Bob Selcoe, Vladimir Shevelev, N. J. A. Sloane, and Reinhard Zumkeller, The Yellowstone Permutation, arXiv preprint arXiv:1501.01669 [math.NT], 2015.
• Index entries for sequences that are permutations of the natural numbers

Crossrefs

Cf. A098550, A098553.

Cf. A249943 (partial maxima).

Cf. A098479, A255940.

Programs

Haskell

import Data.List (elemIndex); import Data.Maybe (fromJust)
a098551 = (+ 1) . fromJust . (`elemIndex` a098550_list)
-- Reinhard Zumkeller, Nov 21 2014

Mathematica

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 *)

Formula

A098553(n) = a(a(n)).