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Inverse permutation to A121216.
3

%I #7 Mar 22 2022 00:10:47

%S 1,2,3,5,4,6,7,9,10,12,8,13,11,16,17,19,14,20,15,23,21,24,18,28,22,27,

%T 25,31,26,36,29,32,33,35,30,40,34,39,37,43,38,44,41,47,48,50,42,54,45,

%U 51,49,55,46,58,52,59,53,62,56,63,57,66,64,67,60,71,61

%N Inverse permutation to A121216.

%C A121216(a(n)) = a(A121216(n)) = n.

%H Reinhard Zumkeller, <a href="/A225047/b225047.txt">Table of n, a(n) for n = 1..10000</a>

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

%o (Haskell)

%o import Data.List (elemIndex)

%o import Data.Maybe (fromJust)

%o a225047 = (+ 1) . fromJust . (`elemIndex` a121216_list)

%K nonn

%O 1,2

%A _Reinhard Zumkeller_, Apr 25 2013