a(1) = 1, a(2) = 2, a(3) = 3, a(n+3) = a(n) + a(n+1).

Terms

a(0) =1a(1) =2a(2) =3a(3) =3a(4) =5a(5) =6a(6) =8a(7) =11a(8) =14a(9) =19a(10) =25a(11) =33a(12) =44a(13) =58a(14) =77a(15) =102a(16) =135a(17) =179a(18) =237a(19) =314a(20) =416a(21) =551a(22) =730a(23) =967a(24) =1281a(25) =1697a(26) =2248a(27) =2978a(28) =3945a(29) =5226