Zeroless analog of tetranacci numbers.

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) =25a(15) =2344a(16) =4339a(17) =85a(18) =6793a(19) =13561a(20) =24778a(21) =45217a(22) =9349a(23) =9295a(24) =88639a(25) =1525a(26) =1888a(27) =11347a(28) =13399a(29) =28159