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a(n) is the position of n in A026166.
2

%I #9 Oct 31 2019 01:32:51

%S 1,2,4,3,7,8,10,5,13,6,16,17,19,20,22,9,25,26,28,11,31,12,34,35,37,14,

%T 40,15,43,44,46,47,49,18,52,53,55,56,58,21,61,62,64,23,67,24,70,71,73,

%U 74,76,27,79,80,82,29,85,30,88,89,91,32,94

%N a(n) is the position of n in A026166.

%C This permutation of the positive integers is the inverse of A026166. - _Clark Kimberling_, Oct 20 2019

%H Clark Kimberling, <a href="/A026167/b026167.txt">Table of n, a(n) for n = 1..10000</a>

%t a[1] = 1; z = 3000;

%t Do[{L, R} = {n - #, n + #} &[Floor[(n - 1)/2]];

%t If[! Head[a[L]] === Integer, a[L] = n, a[R] = n], {n, 2, z}];

%t a026166 = Most[Last[

%t Last[Reap[NestWhile[# + 1 &, 1, Head[Sow[a[#]]] === Integer &]]]]]; (* A026166 *)

%t Flatten[Table[Position[a026166, n], {n, 1, 1000}]] (* A026167 *)

%t (* _Peter J. C. Moses_, Oct 20 2019 *)

%Y Cf. A026166.

%K nonn

%O 1,2

%A _Clark Kimberling_