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

Terms

a(0) =1a(1) =1a(2) =1a(3) =1a(4) =4a(5) =7a(6) =13a(7) =25a(8) =49a(9) =94a(10) =181a(11) =349a(12) =673a(13) =1297a(14) =2500a(15) =4819a(16) =9289a(17) =17905a(18) =34513a(19) =66526a(20) =128233a(21) =247177a(22) =476449a(23) =918385a(24) =1770244a(25) =3412255a(26) =6577333a(27) =12678217a(28) =24438049a(29) =47105854