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 A249777 Let z = A084937: a(n) = number of numbers <= z(n) that are != z(k) for k=1..n-1 and not coprime to z(n-1) and z(n-2). 8
 0, 0, 0, 1, 0, 1, 2, 1, 2, 3, 0, 5, 6, 0, 6, 7, 3, 2, 10, 1, 5, 6, 3, 7, 10, 0, 10, 13, 0, 13, 16, 0, 5, 15, 1, 11, 16, 1, 6, 15, 2, 11, 16, 4, 16, 17, 2, 17, 12, 5, 16, 17, 3, 17, 18, 0, 20, 21, 0, 23, 28, 0, 23, 27, 1, 15, 30, 3, 17, 26, 4, 19, 28, 2, 21 (list; graph; refs; listen; history; text; internal format)
 OFFSET 1,7 COMMENTS a(A249684(n)) = 0. LINKS Reinhard Zumkeller, Table of n, a(n) for n = 1..10000 EXAMPLE .   n | A084937(n) |    unused numbers less than A084937(n)   | 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                      |    5 .  13 |         19 |  10, 12, 14, 15, 16, 18                  |    6 .  14 |         10 |  _                                       |    0 .  15 |         21 |  12, 14, 15, 16, 18, 20                  |    6 .  16 |         23 |  12, 14, 15, 16, 18, 20, 22              |    7 .  17 |         16 |  12, 14, 15                              |    3 .  18 |         15 |  12, 14                                  |    2 .  19 |         29 |  12, 14, 18, 20, 22, 24, 25, 26, 27, 28  |   10 .  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  |   10 . PROG (Haskell) a249777 n = a249777_list !! (n-1) a249777_list = 0 : 0 : f 2 1 [3..] where    f x y zs = g zs 0 where       g (u:us) w | gcd y u > 1 || gcd x u > 1 = g us (w + 1)                  | otherwise = w : f u x (delete u zs) CROSSREFS Cf. A084937, A249684. Sequence in context: A249858 A249857 A317441 * A289065 A132815 A167684 Adjacent sequences:  A249774 A249775 A249776 * A249778 A249779 A249780 KEYWORD nonn AUTHOR Reinhard Zumkeller, Nov 05 2014 STATUS approved

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Last modified April 16 18:53 EDT 2021. Contains 343050 sequences. (Running on oeis4.)