%I #14 Feb 03 2023 01:35:11

%S 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,

%T 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,

%U 11,12,10,12,11,6,13,12,11,12,10,12,11,12,13,9,12,11,13,12,10

%N a(n) is the smallest j for which 2^j kara n is defined (see A053405).

%H Reinhard Zumkeller, <a href="/A053087/b053087.txt">Table of n, a(n) for n = 1..1000</a>

%e a(6)=4 because 2^3 kara 6 is undefined, but 16 kara 6 = 3.

%o (Haskell)

%o a053087 n = head [j | j <- [0..], (2 ^ j) `kara` n /= Nothing] where

%o kara a b = if null ks then Nothing else Just $ head ks

%o where ks = [c | c <- [1..a], a <= c * b, a > c * (b - 1)]

%o -- _Reinhard Zumkeller_, Mar 30 2013

%Y Cf. A053405.

%Y A053092(n) = 2^a(n) kara n.

%K nonn,look

%O 1,3

%A Robert Lozyniak (11(AT)onna.com), Feb 26 2000

%E More terms from Antony M. Goddard, cat(AT)animal.u-net.com or tony(AT)noggin.lowtech.org, Oct 13 2000