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A053087
a(n) is the smallest j for which 2^j kara n is defined (see A053405).
3
0, 1, 3, 2, 5, 4, 5, 3, 7, 6, 5, 7, 6, 8, 7, 4, 9, 8, 7, 8, 9, 6, 9, 8, 9, 7, 9, 10, 8, 10, 9, 5, 11, 10, 9, 10, 8, 10, 11, 9, 10, 11, 7, 11, 10, 11, 9, 11, 10, 11, 12, 8, 11, 10, 12, 11, 9, 12, 11, 12, 10, 12, 11, 6, 13, 12, 11, 12, 10, 12, 11, 12, 13, 9, 12, 11, 13, 12, 10
OFFSET
1,3
LINKS
EXAMPLE
a(6)=4 because 2^3 kara 6 is undefined, but 16 kara 6 = 3.
PROG
(Haskell)
a053087 n = head [j | j <- [0..], (2 ^ j) `kara` n /= Nothing] where
kara a b = if null ks then Nothing else Just $ head ks
where ks = [c | c <- [1..a], a <= c * b, a > c * (b - 1)]
-- Reinhard Zumkeller, Mar 30 2013
CROSSREFS
Cf. A053405.
A053092(n) = 2^a(n) kara n.
Sequence in context: A061313 A259846 A087669 * A316519 A062327 A075491
KEYWORD
nonn,look
AUTHOR
Robert Lozyniak (11(AT)onna.com), Feb 26 2000
EXTENSIONS
More terms from Antony M. Goddard, cat(AT)animal.u-net.com or tony(AT)noggin.lowtech.org, Oct 13 2000
STATUS
approved