A141355 The Jacobsthal sequence, dropping each third term.

1, 1, 5, 11, 43, 85, 341, 683, 2731, 5461, 21845, 43691, 174763, 349525, 1398101, 2796203, 11184811, 22369621, 89478485, 178956971, 715827883, 1431655765, 5726623061, 11453246123, 45812984491, 91625968981, 366503875925, 733007751851

Offset

0,3

Comments

A001045 after removal of the subsequence A132805.

Links

Table of n, a(n) for n=0..27.

Formula

a(2n+1)-a(2n) = 6*A015565(n).

a(4n+1)=2a(4n)-1. a(4n+2)=4a(4n+1)+1. a(4n+3)=2a(4n+2)+1. a(4n+4)=4a(4n+3)-1.

a(2n)= A082311(n). a(2n+1) = A082365(n). - R. J. Mathar, Feb 23 2009

a(n)=7*a(n-2)+8*a(n-4). G.f.: (1+x-2*x^2+4*x^3)/((1-8*x^2)*(1+x^2)). - R. J. Mathar, Feb 23 2009

Crossrefs

Sequence in context: A260268 A129015 A209976 * A262020 A222368 A333114

Adjacent sequences: A141352 A141353 A141354 * A141356 A141357 A141358

Keyword

nonn,easy

Author

Paul Curtz, Aug 03 2008

Extensions

Edited and extended by R. J. Mathar, Feb 23 2009

Status

approved