

A186444


The count of numbers <= n for which 3 is an infinitary divisor.


3



0, 0, 1, 1, 1, 2, 2, 2, 2, 2, 2, 3, 3, 3, 4, 4, 4, 4, 4, 4, 5, 5, 5, 6, 6, 6, 7, 7, 7, 8, 8, 8, 9, 9, 9, 9, 9, 9, 10, 10, 10, 11, 11, 11, 11, 11, 11, 12, 12, 12, 13, 13, 13, 14, 14, 14, 15, 15, 15, 16, 16, 16, 16, 16, 16, 17, 17, 17, 18, 18, 18, 18, 18, 18, 19
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OFFSET

1,6


COMMENTS

For the definition of infinitary divisors, see A037445.
The sequence is the partial sums of the characteristic function of the numbers with 3 as one of the infinitary divisors; these are 3, 6, 12, 15, 21, 24, 27, 30 etc, apparently shown in A145204.  R. J. Mathar, Feb 28 2011


LINKS

Amiram Eldar, Table of n, a(n) for n = 1..10000


FORMULA

a(n) = floor(n/3)  a(floor(n/3)).
a(n) = floor(n/3)  floor(n/9) + floor(n/27)  ....
a(n) grows as n/4 as n tends to infinity.


MAPLE

A186444 := proc(n) local a, k ; option remember; if n< 3 then 0; else floor(n/3) procname(floor(n/3)) ; end if; end proc: # R. J. Mathar, Feb 28 2011


CROSSREFS

Cf. A123087, A037445.
Sequence in context: A235122 A131996 A090618 * A072748 A174631 A278949
Adjacent sequences: A186441 A186442 A186443 * A186445 A186446 A186447


KEYWORD

nonn


AUTHOR

Vladimir Shevelev, Feb 21 2011


STATUS

approved



