A Jacobsthal number sequence.

Terms

a(0) =1a(1) =11a(2) =85a(3) =683a(4) =5461a(5) =43691a(6) =349525a(7) =2796203a(8) =22369621a(9) =178956971a(10) =1431655765a(11) =11453246123a(12) =91625968981a(13) =733007751851