Tribonacci numbers: a(n) = a(n-1) + a(n-2) + a(n-3) for n >= 3 with a(0) = a(1) = 0 and a(2) = 1.

Terms

a(0) =0a(1) =0a(2) =1a(3) =1a(4) =2a(5) =4a(6) =7a(7) =13a(8) =24a(9) =44a(10) =81a(11) =149a(12) =274a(13) =504a(14) =927a(15) =1705a(16) =3136a(17) =5768a(18) =10609a(19) =19513a(20) =35890a(21) =66012a(22) =121415a(23) =223317a(24) =410744a(25) =755476a(26) =1389537a(27) =2555757a(28) =4700770a(29) =8646064