The number of bits needed to write n using Elias gamma coding. - Charles R Greathouse IV, Mar 21 2012

Consists of the n-th odd number (A005408(n) = 2n+1) repeated 2^(n-1) times (since a(n) = a(n-1) except when a(n) > a(n-1) which happens for n a power of 2). - Jonathan Vos Post, Jun 17 2007