cp's OEIS Frontend

A080712 a(0) = 4; 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 A080712 #10 Mar 30 2012 17:27:40
%S A080712 4,5,7,8,9,12,13,15,18,21,22,23,24,27,28,30,31,32,33,34,35,36,39,42,
%T A080712 45,46,47,48,51,52,54,57,60,63,66,69,72,73,74,75,76,77,78,79,80,81,84,
%U A080712 87,90,91,92,93,96,97,99,100,101,102,103,104,105,106,107,108,109,110,111
%N A080712 a(0) = 4; 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 A080712 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 A080712 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 A080712 <a href="/index/Aa#aan">Index entries for sequences of the a(a(n)) = 2n family</a>
%F A080712 a(a(n)) = 3*(n+3).
%o A080712 (PARI) {a=4; m=[4]; for(n=1,67,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 A080712 Cf. A079000, A003605, A079253, A080711, A080710.
%K A080712 nonn,easy
%O A080712 0,1
%A A080712 _N. J. A. Sloane_, Mar 05 2003
%E A080712 More terms and PARI code from _Klaus Brockhaus_, Mar 06 2003