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A322837 Number of positive integers less than n with fewer distinct prime factors than n. 3
0, 1, 1, 1, 1, 5, 1, 1, 1, 8, 1, 9, 1, 10, 10, 1, 1, 12, 1, 13, 13, 13, 1, 14, 1, 15, 1, 16, 1, 29, 1, 1, 19, 19, 19, 19, 1, 20, 20, 20, 1, 40, 1, 22, 22, 22, 1, 23, 1, 24, 24, 24, 1, 25, 25, 25, 25, 25, 1, 57, 1, 27, 27, 1, 28, 62, 1, 29, 29, 65, 1, 30, 1, 31 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,6

LINKS

Table of n, a(n) for n=1..74.

EXAMPLE

Column n lists the a(n) positive integers less than n with fewer distinct prime factors than n:

  1  2  3  4  5  6  7  8  9  10  11  12  13  14  15  16  17  18  19  20

  ---------------------------------------------------------------------

     1  1  1  1  5  1  1  1  9   1   11  1   13  13  1   1   17  1   19

                 4           8       9       11  11          16      17

                 3           7       8       9   9           13      16

                 2           5       7       8   8           11      13

                 1           4       5       7   7           9       11

                             3       4       5   5           8       9

                             2       3       4   4           7       8

                             1       2       3   3           5       7

                                     1       2   2           4       5

                                             1   1           3       4

                                                             2       3

                                                             1       2

                                                                     1

MATHEMATICA

Table[Length[Select[Range[n], PrimeNu[#]<PrimeNu[n]&]], {n, 100}]

CROSSREFS

Positions of 1's are A246655.

Cf. A000010, A001221, A006049, A067003, A294277, A294278, A302242, A322838, A322841.

Sequence in context: A028236 A066504 A292771 * A168677 A140210 A010130

Adjacent sequences:  A322834 A322835 A322836 * A322838 A322839 A322840

KEYWORD

nonn

AUTHOR

Gus Wiseman, Dec 28 2018

STATUS

approved

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Last modified April 5 03:58 EDT 2020. Contains 333238 sequences. (Running on oeis4.)