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%I #15 Feb 14 2018 18:29:24
%S 1,2,5,3,6,4,17,8,10,7,18,9,23,20,11,13,24,15,58,12,16,19,59,14,33,22,
%T 28,21,62,26,63,31,29,25,34,36,66,57,39,32,67,35,72,30,27,60,125,37,
%U 49,44,40,38,126,47,45,42,71,61,131,56,134,64,48,52,80,46,135,41,76,43
%N Inverse permutation to A075075.
%C This is a permutation of the positive integers (provided A075075 really is a permutation).
%H H. v. Eitzen, <a href="/A160516/b160516.txt">Table of n, a(n) for n = 1..50000</a>
%F A075075(a(n)) = n.
%e A075075(7) = 10, therefore a(10) = 7.
%e A075055(17) = 7, therefore a(7) = 17.
%t f[s_List] := Block[{m = Numerator[s[[ -1]]/s[[ -2]]]}, k = m; While[MemberQ[s, k], k += m]; Append[s, k]]; s = Nest[f, {1, 2}, 200]; Table[ Position[s, n, 1, 1], {n, 70}] // Flatten (* _Robert G. Wilson v_, May 20 2009 *)
%o (Haskell)
%o import Data.List (elemIndex)
%o import Data.Maybe (fromJust)
%o a160516 = (+ 1) . fromJust . (`elemIndex` a075075_list)
%o -- _Reinhard Zumkeller_, Dec 19 2012
%Y Cf. A185635 (fixed points).
%K nonn
%O 1,2
%A _Hagen von Eitzen_, May 16 2009
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