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

1,3

Links

Reinhard Zumkeller, Table of n, a(n) for n = 1..1000

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

Adjacent sequences: A053084 A053085 A053086 * A053088 A053089 A053090

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