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A100752 a(n) is the number of positive integers <= 10^n that are divisible by no prime exceeding 3. 5
1, 7, 20, 40, 67, 101, 142, 190, 244, 306, 376, 452, 534, 624, 720, 824, 935, 1052, 1178, 1309, 1447, 1593, 1745, 1905, 2071, 2244, 2424, 2611, 2806, 3006, 3214, 3429, 3652, 3881, 4117, 4360, 4610, 4866, 5131, 5401, 5679, 5964, 6255, 6553, 6859, 7172, 7491 (list; graph; refs; listen; history; text; internal format)
OFFSET

0,2

LINKS

David A. Corneth, Table of n, a(n) for n = 0..1999

EXAMPLE

a(1) = 7 as there are 7 3-smooth numbers less than 10^1 = 10; they are 1, 2, 3, 4, 6, 8, 9. - David A. Corneth, Nov 14 2019

MATHEMATICA

f[n_] := Sum[ Floor@ Log[2, n/3^i] + 1, {i, 0, Log[3, n]}]; Table[ f[10^n], {n, 0, 46}] (* Robert G. Wilson v, Nov 07 2012 *)

CROSSREFS

Cf. A066343, A106598, A106600, A107352, A106629.

Row 2 of A253635.

Cf. A003586, A011557.

Sequence in context: A140676 A025056 A038349 * A162024 A143058 A298488

Adjacent sequences:  A100749 A100750 A100751 * A100753 A100754 A100755

KEYWORD

nonn

AUTHOR

Robert G. Wilson v, May 27 2005

STATUS

approved

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Last modified May 27 17:53 EDT 2020. Contains 334664 sequences. (Running on oeis4.)