A080353 - OEIS

A080353

a(1)=5; for n>1, a(n)=a(n-1)+1 if n is already in the sequence, a(n)=a(n-1)+2 otherwise.

%I #9 Oct 08 2018 02:39:22

%S 5,7,9,11,12,14,15,17,18,20,21,22,24,25,26,28,29,30,32,33,34,35,37,38,

%T 39,40,42,43,44,45,47,48,49,50,51,53,54,55,56,57,59,60,61,62,63,65,66,

%U 67,68,69,70,72,73,74,75,76,77,79,80,81,82,83,84,86,87,88,89

%N a(1)=5; for n>1, a(n)=a(n-1)+1 if n is already in the sequence, a(n)=a(n-1)+2 otherwise.

%H B. Cloitre, N. J. A. Sloane and M. J. Vandermast, <a href="http://www.cs.uwaterloo.ca/journals/JIS/index.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) = n + floor(sqrt(6*n)) + O(1).

%t a[1] = 5; a[n_] := a[n] = If[MemberQ[Array[a, n-1], n], a[n-1]+1, a[n-1]+2]; Array[a, 67] (* _Jean-François Alcover_, Oct 08 2018 *)

%Y Cf. A080036, A080037. Differences give A080354.

%K nonn

%O 1,1

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