1,1

a(n) = 4*3^((n-1)/2)-2 (n odd), 2*3^(n/2)-2 (n even).

Cf. A050250.

Sequence in context: A141138 A077627 A153927 this_sequence A105024 A050871 A077635

Adjacent sequences: A117859 A117860 A117861 this_sequence A117863 A117864 A117865

nonn

Martin Renner (martin.renner(AT)gmx.net), May 02 2006