a(n) = floor(A026532(n)/5).

Terms

a(0) =0a(1) =0a(2) =1a(3) =3a(4) =7a(5) =21a(6) =43a(7) =129a(8) =259a(9) =777a(10) =1555a(11) =4665a(12) =9331a(13) =27993a(14) =55987a(15) =167961a(16) =335923a(17) =1007769a(18) =2015539a(19) =6046617a(20) =12093235a(21) =36279705a(22) =72559411a(23) =217678233a(24) =435356467a(25) =1306069401a(26) =2612138803a(27) =7836416409a(28) =15672832819a(29) =47018498457