A053087 a(n) is the smallest j for which 2^j kara n is defined (see A053405).
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
Examples
a(6)=4 because 2^3 kara 6 is undefined, but 16 kara 6 = 3.
Links
- Reinhard Zumkeller, Table of n, a(n) for n = 1..1000
Programs
-
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
Extensions
More terms from Antony M. Goddard, cat(AT)animal.u-net.com or tony(AT)noggin.lowtech.org, Oct 13 2000