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%I #20 Mar 17 2019 03:24:52
%S 1,2,5,3,30,6,28,4,38,26,11,7,36,29,14,8,201,39,34,27,180,12,175,9,
%T 199,37,46,31,25,15,178,10,242,202,49,40,197,35,54,32,192,158,23,13,
%U 208,176,57,16,240,200,61,41,83,47,195,33,121,42,67,17,190,179,70,18,689,243
%N In A109732, the number 2n+1 appears in position a(n).
%H N. J. A. Sloane and Alois P. Heinz, <a href="/A109734/b109734.txt">Table of n, a(n) for n = 0..20000</a> (first 1024 terms from N. J. A. Sloane)
%e 9 appears in position 30 in A109732, so a(4) = 30.
%p with(LinearAlgebra);
%p hit:=Array(1..200000); a:=[1,3,7];
%p hit[1]:=1; hit[3]:=2; hit[7]:=3; S:={15}; L:=7;
%p for n from 4 to 20000 do
%p if (L mod 3 = 0) and hit[L/3]=0 then
%p L:=L/3; a:=[op(a),L]; hit[L]:=n; S:= S minus {L};
%p if hit[2*L+1]=0 then S:=S union {2*L+1}; fi;
%p else L:=min(S); a:=[op(a),L]; hit[L]:=n; S:=S minus {L};
%p if hit[2*L+1]=0 then S:=S union {2*L+1}; fi;
%p fi;
%p od:
%p #a;
%p w:=[];
%p for i from 0 to 50000 do
%p if hit[2*i+1]=0 then break; fi;
%p w:=[op(w),hit[2*i+1]]; od:
%p w; # _N. J. A. Sloane_, Aug 25 2015
%t (* using the M generated in A109732 *) ms=Sort[M]; k=1; While[ms[[k]]==2k-1, k++ ]; k=k-1; Take[Ordering[M], k] (* _T. D. Noe_, Aug 10 2005 *)
%Y Cf. A109732. For records see A109739 and A109740.
%K nonn
%O 0,2
%A _N. J. A. Sloane_, Aug 10 2005
%E More terms from _T. D. Noe_ and _Ray Chandler_, Aug 10 2005
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