%I #13 Aug 21 2015 11:05:31
%S 1,2,4,3,7,5,9,11,14,8,13,6,17,10,19,12,21,15,23,25,27,29,31,33,38,18,
%T 36,43,41,20,35,45,47,22,51,16,53,24,49,26,40,28,50,30,57,32,59,34,55,
%U 39,65,61,63,37,67,44,71,42,75,69,77,73,79,46,81,48,85
%N Smallest m such that A257905(m) = n.
%C Conjectured inverse of A257905.
%H Reinhard Zumkeller, <a href="/A256283/b256283.txt">Table of n, a(n) for n = 0..1000</a>
%t {a, f} = {{1}, {0}}; Do[tmp = {#, # - Last[a]} &[Min[Complement[#, Intersection[a, #]]&[Last[a] + Complement[#, Intersection[f, #]] &[Range[2 - Last[a], -1]]]]];
%t If[! IntegerQ[tmp[[1]]], tmp = {Last[a] + #, #} &[NestWhile[# + 1 &, 1, ! (! MemberQ[f, #] && ! MemberQ[a, Last[a] - #]) &]]];
%t AppendTo[a, tmp[[1]]]; AppendTo[f, tmp[[2]]], {1000}]; a;
%t Flatten[Table[Position[a, n], {n, 1, 150}]]) (* _Peter J. C. Moses_, May 14 2015 *)
%o (Haskell)
%o import Data.List (elemIndex); import Data.Maybe (fromJust)
%o a256283 = (+ 1) . fromJust . (`elemIndex` a257905_list)
%Y Cf. A257905.
%K nonn
%O 0,2
%A _Reinhard Zumkeller_, Jun 03 2015