A080640 - OEIS

A080640

a(1) = 3; for n>1, a(n) is taken to be the smallest 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 divisible by 4".

%I #16 Nov 06 2025 23:39:57

%S 3,5,8,9,12,13,14,16,20,21,22,24,28,32,33,36,37,38,39,40,44,48,49,52,

%T 53,54,55,56,57,58,59,60,64,65,66,68,72,76,80,84,85,86,87,88,89,90,91,

%U 92,96,97,98,100,104,108,112,116,120,124,128,132,133,134,135,136,140,144

%N a(1) = 3; for n>1, a(n) is taken to be the smallest 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 divisible by 4".

%H Benoit Cloitre, N. J. A. Sloane and Matthew J. Vandermast, <a href="https://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 Benoit Cloitre, N. J. A. Sloane and Matthew J. Vandermast, <a href="https://arxiv.org/abs/math/0305308">Numerical analogues of Aronson's sequence</a>, arXiv:math/0305308 [math.NT], 2003.

%H <a href="/index/Aa#aan">Index entries for sequences of the a(a(n)) = 2n family</a>

%F {a(a(n))} = {6, 4i, i >= 3}.

%Y Cf. A080639, A079000.

%K nonn,easy

%O 1,1

%A _N. J. A. Sloane_ and _Benoit Cloitre_, Feb 28 2003

%E More terms from _Matthew Vandermast_, Feb 28 2003