a(n) = floor(A026549(n)/5).

Terms

a(0) =0a(1) =0a(2) =1a(3) =2a(4) =7a(5) =14a(6) =43a(7) =86a(8) =259a(9) =518a(10) =1555a(11) =3110a(12) =9331a(13) =18662a(14) =55987a(15) =111974a(16) =335923a(17) =671846a(18) =2015539a(19) =4031078a(20) =12093235a(21) =24186470a(22) =72559411a(23) =145118822a(24) =435356467a(25) =870712934a(26) =2612138803a(27) =5224277606a(28) =15672832819a(29) =31345665638