Modified quadranacci series.

Terms

a(0) =0a(1) =1a(2) =1a(3) =1a(4) =1a(5) =2a(6) =2a(7) =2a(8) =3a(9) =4a(10) =4a(11) =6a(12) =7a(13) =8a(14) =12a(15) =14a(16) =15a(17) =23a(18) =27a(19) =29a(20) =44a(21) =52a(22) =56a(23) =85a(24) =100a(25) =108a(26) =164a(27) =193a(28) =208a(29) =316