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A249856
Let z = A084937: a(n) = number of odd 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, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 1, 1, 1, 0, 2, 0, 0, 0, 0, 0, 1, 0, 1, 2, 0, 2, 3, 0, 0, 2, 0, 1, 2, 0, 0, 1, 0, 0, 1, 0, 1, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 1, 1, 0, 2, 4, 0, 2, 3, 0, 0, 4, 0, 0, 2, 0, 0, 2, 0, 0, 1, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0
OFFSET
1,19
COMMENTS
a(n) = A249777(n) - A249857(n).
PROG
(Haskell)
a249856 = sum . map (flip mod 2) . (uss !!)
uss = [] : [] : [] : f 2 1 [3..] where
f x y zs = g zs [] where
g (v:vs) ws | gcd v y > 1 || gcd v x > 1 = g vs (v : ws)
| otherwise = ws : f v x (delete v zs)
CROSSREFS
For a different way to look at the missing numbers in A084937, see A249686, A250099, A250100.
Sequence in context: A363742 A033772 A086015 * A086012 A248394 A368843
KEYWORD
nonn
AUTHOR
Reinhard Zumkeller, Nov 09 2014
STATUS
approved