A080199 - OEIS

%I #12 Feb 13 2019 07:53:27

%S 1,7,13,19,25,31,28,34,40,46,52,58,55,61,67,73,79,85,82,88,94,100,106,

%T 112,109,115,121,118,124,130,127,133,139,136,142,148,154,160,166,163,

%U 169,175,181,187,193,190,196,202,208,214,220,217,223,229

%N a(1)=1; for n>1, a(n)=a(n-1) - 3 if n is already in the sequence, a(n)=a(n-1) + 6 otherwise.

%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> (math.NT/0305308)

%F a(n) = 3*n*(1 + 1/log_3(n)) + o(n).

%t a[1] = 1;

%t a[n_] := a[n] = If[MemberQ[Array[a, n-1], n], a[n-1]-3, a[n-1]+6];

%t Array[a, 54] (* _Jean-François Alcover_, Feb 13 2019 *)

%Y Cf. A080455-A080458, A080036, A080037.

%K nonn

%O 1,2

%A _N. J. A. Sloane_, Mar 20 2003