Triangular "Fibonacci array".

Terms

a(0) =0a(1) =1a(2) =1a(3) =1a(4) =2a(5) =1a(6) =2a(7) =3a(8) =3a(9) =2a(10) =3a(11) =5a(12) =4a(13) =5a(14) =3a(15) =5a(16) =8a(17) =7a(18) =7a(19) =8a(20) =5a(21) =8a(22) =13a(23) =11a(24) =12a(25) =11a(26) =13a(27) =8a(28) =13a(29) =21