%I #10 Mar 30 2012 17:27:40
%S 2,4,6,7,9,10,12,15,16,18,21,22,24,25,26,27,30,31,33,34,35,36,39,40,
%T 42,45,48,51,52,53,54,57,58,60,63,66,69,70,71,72,75,76,78,79,80,81,82,
%U 83,84,85,86,87,90,93,96,97,98,99,102,103,105,106,107,108,109,110,111,112
%N a(0) = 2; for n>0, a(n) is taken to be the smallest positive integer greater than a(n-1) which is consistent with the condition "n is a member of the sequence if and only if a(n) is a multiple of 3".
%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)
%H <a href="/index/Aa#aan">Index entries for sequences of the a(a(n)) = 2n family</a>
%F a(a(n)) = 3*(n+2).
%o (PARI) {a=2; m=[2]; for(n=1,68,print1(a,","); a=a+1; if(m[1]==n, while(a%3>0,a++); m=if(length(m)==1,[],vecextract(m,"2..")),if(a%3==0,a++)); m=concat(m,a))}
%Y Cf. A079000, A003605, A079253, A080710, A080712.
%K nonn,easy
%O 0,1
%A _N. J. A. Sloane_, Mar 05 2003
%E More terms and PARI code from _Klaus Brockhaus_, Mar 06 2003