cp's OEIS Frontend

A080720 a(0) = 5; 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".

%I A080720 #10 Mar 30 2012 17:27:40
%S A080720 5,7,8,10,11,12,13,15,18,19,21,24,27,30,31,33,34,35,36,39,40,42,43,44,
%T A080720 45,46,47,48,49,50,51,54,55,57,60,63,66,67,68,69,72,73,75,78,81,84,87,
%U A080720 90,93,96,99,102,103,104,105,108,109,111,112,113,114,115,116,117,118,119
%N A080720 a(0) = 5; 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 A080720 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 A080720 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 A080720 <a href="/index/Aa#aan">Index entries for sequences of the a(a(n)) = 2n family</a>
%F A080720 a(a(n)) = 3*(n+4).
%o A080720 (PARI) {a=5; m=[5]; for(n=1,66,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 A080720 Cf. A079000, A003605, A079253, A080711, A080710.
%K A080720 nonn,easy
%O A080720 0,1
%A A080720 _N. J. A. Sloane_, Mar 05 2003
%E A080720 More terms and PARI code from _Klaus Brockhaus_, Mar 07 2003