Tetranacci numbers: a(n) = a(n-1) + a(n-2) + a(n-3) + a(n-4), with a(0)=a(1)=0, a(2)=1, a(3)=2.

Terms

a(0) =0a(1) =0a(2) =1a(3) =2a(4) =3a(5) =6a(6) =12a(7) =23a(8) =44a(9) =85a(10) =164a(11) =316a(12) =609a(13) =1174a(14) =2263a(15) =4362a(16) =8408a(17) =16207a(18) =31240a(19) =60217a(20) =116072a(21) =223736a(22) =431265a(23) =831290a(24) =1602363a(25) =3088654a(26) =5953572a(27) =11475879a(28) =22120468a(29) =42638573