Esanacci (hexanacci or "6-anacci") numbers.

Terms

a(0) =6a(1) =1a(2) =3a(3) =7a(4) =15a(5) =31a(6) =63a(7) =120a(8) =239a(9) =475a(10) =943a(11) =1871a(12) =3711a(13) =7359a(14) =14598a(15) =28957a(16) =57439a(17) =113935a(18) =225999a(19) =448287a(20) =889215a(21) =1763832a(22) =3498707a(23) =6939975a(24) =13766015a(25) =27306031a(26) =54163775a(27) =107438335a(28) =213112838a(29) =422726969