a(n) = 2*a(n-1) - a(n-4) + a(n-5) with a(-1)=a(0)=a(1)=1, a(2)=2, a(3)=4, a(4)=7.

Terms

a(0) =1a(1) =1a(2) =1a(3) =2a(4) =4a(5) =7a(6) =14a(7) =27a(8) =52a(9) =101a(10) =195a(11) =377a(12) =729a(13) =1409a(14) =2724a(15) =5266a(16) =10180a(17) =19680a(18) =38045a(19) =73548a(20) =142182a(21) =274864a(22) =531363a(23) =1027223a(24) =1985812a(25) =3838942a(26) =7421385a(27) =14346910a(28) =27735231a(29) =53617332