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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 (list; graph; refs; listen; history; text; internal format)
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

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Last modified August 11 19:16 EDT 2020. Contains 336428 sequences. (Running on oeis4.)