%I #9 Mar 03 2016 15:28:12

%S 1,6,11,16,21,17,22,27,32,37,33,38,43,48,53,49,45,50,55,60,56,52,57,

%T 62,67,72,68,73,78,83,88,84,80,85,90,95,91,87,92,97,102,107,103,108,

%U 104,109,114,110,106,102,107,103,99,104,100,96,92,97,102,98,103,99

%N a(1)=1; for n>1, a(n)=a(n-1)-4 if n is already in the sequence, a(n)=a(n-1)+5 otherwise.

%C a(n)-n is eventually periodic with period 18. - _Ivan Neretin_, Mar 03 2016

%H Ivan Neretin, <a href="/A080904/b080904.txt">Table of n, a(n) for n = 1..1000</a>

%H B. Cloitre, N. J. A. Sloane and M. J. Vandermast, <a href="http://www.cs.uwaterloo.ca/journals/JIS/VOL6/Cloitre/cloitre2.html">Numerical analogues of Aronson's sequence</a>, J. Integer Seqs., Vol. 6 (2003), #03.2.2.

%H B. Cloitre, N. J. A. Sloane and M. J. Vandermast, <a href="http://arXiv.org/abs/math.NT/0305308">Numerical analogues of Aronson's sequence</a>, arXiv:math/0305308 [math.NT], 2003.

%t Fold[Append[#1, #1[[-1]] + If[MemberQ[#1, #2], -4, 5]] &, {1}, Range[2, 62]] (* _Ivan Neretin_, Mar 03 2016 *)

%Y Cf. A080578, A080900.

%K nonn

%O 1,2

%A _Benoit Cloitre_, Apr 01 2003