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A080029
a(n) is taken to be the smallest positive integer not already present which is consistent with the condition "n is a member of the sequence if and only if a(n) is a multiple of 3".
5
0, 2, 3, 6, 5, 9, 12, 8, 15, 18, 11, 21, 24, 14, 27, 30, 17, 33, 36, 20, 39, 42, 23, 45, 48, 26, 51, 54, 29, 57, 60, 32, 63, 66, 35, 69, 72, 38, 75, 78, 41, 81, 84, 44, 87, 90, 47, 93, 96, 50, 99, 102, 53, 105, 108, 56, 111, 114, 59, 117, 120, 62, 123, 126, 65, 129, 132, 68
OFFSET
0,2
LINKS
B. Cloitre, N. J. A. Sloane and M. J. Vandermast, Numerical analogues of Aronson's sequence, J. Integer Seqs., Vol. 6 (2003), #03.2.2.
B. Cloitre, N. J. A. Sloane and M. J. Vandermast, Numerical analogues of Aronson's sequence, arXiv:math/0305308 [math.NT], 2003.
FORMULA
a(3m)=6m, a(3m+1)=3m+2, a(3m+2)=6m+3.
MATHEMATICA
{#+1, 2#-1, 2#}[[Mod[ #, 3, 1]]]&/@Range[0, 80] (* Federico Provvedi, Jun 15 2021 *)
PROG
(Python)
def a(n): m, r = divmod(n, 3); return 3*(2-r%2)*m + (r > 0)*(r+1)
print([a(n) for n in range(68)]) # Michael S. Branicky, Jun 15 2021
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
N. J. A. Sloane, Mar 14 2003
EXTENSIONS
More terms from Matthew Vandermast, Mar 20 2003
STATUS
approved