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A249857 Let z = A084937: a(n) = number of even numbers <= z(n) that are != z(k) for k=1..n-1 and not coprime to z(n-1) and z(n-2). 7
0, 0, 0, 1, 0, 1, 2, 1, 2, 3, 0, 4, 5, 0, 5, 6, 2, 2, 8, 1, 5, 6, 3, 7, 9, 0, 9, 11, 0, 11, 13, 0, 5, 13, 1, 10, 14, 1, 6, 14, 2, 11, 15, 4, 15, 16, 2, 16, 12, 5, 16, 17, 3, 17, 18, 0, 19, 20, 0, 21, 24, 0, 21, 24, 1, 15, 26, 3, 17, 24, 4, 19, 26, 2, 21, 26 (list; graph; refs; listen; history; text; internal format)
OFFSET

1,7

COMMENTS

a(n) = A249777(n) - A249856(n).

LINKS

Table of n, a(n) for n=1..76.

EXAMPLE

.     |            |     unused even numbers <  A084937(n)    |

.   n | A084937(n) |     [uncounted odd terms in brackets]    | a(n)

. ----+------------+------------------------------------------+-----

.   3 |          3 |  _                                       |    0

.   4 |          5 |  4                                       |    1

.   5 |          4 |  _                                       |    0

.   6 |          7 |  6                                       |    1

.   7 |          9 |  6,8                                     |    2

.   8 |          8 |  6                                       |    1

.   9 |         11 |  6,10                                    |    2

.  10 |         13 |  6,10,12                                 |    3

.  11 |          6 |  _                                       |    0

.  12 |         17 |  10,12,14,[15],16                        |    4

.  13 |         19 |  10,12,14,[15],16,18                     |    5

.  14 |         10 |  _                                       |    0

.  15 |         21 |  12,14,[15],16,18,20                     |    5

.  16 |         23 |  12,14,[15],16,18,20,22                  |    6

.  17 |         16 |  12,14,[15]                              |    2

.  18 |         15 |  12,14                                   |    2

.  19 |         29 |  12,14,18,20,22,24,[25],26,[27],28       |    8

.  20 |         14 |  12                                      |    1

.  21 |         25 |  12,18,20,22,24                          |    5

.  22 |         27 |  12,18,20,22,24,26                       |    6

.  23 |         22 |  12,18,20                                |    3

.  24 |         31 |  12,18,20,24,26,28,30                    |    7

.  25 |         35 |  12,18,20,24,26,28,30,32,[33],34         |    9 .

PROG

(Haskell)

a249857 = sum . map ((1 -) . flip mod 2) . (uss !!)

-- See A249856 for definition of uss.

CROSSREFS

Cf. A084937, A249777, A249856, A249858.

For a different way to look at the missing numbers in A084937, see A249686, A250099, A250100.

Sequence in context: A273516 A082501 A249858 * A249777 A289065 A132815

Adjacent sequences:  A249854 A249855 A249856 * A249858 A249859 A249860

KEYWORD

nonn

AUTHOR

Reinhard Zumkeller, Nov 09 2014

STATUS

approved

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Last modified October 18 10:28 EDT 2017. Contains 293507 sequences.