The number of 2-compositions of n of Carlitz type.

Terms

a(0) =1a(1) =2a(2) =5a(3) =18a(4) =53a(5) =162a(6) =505a(7) =1548a(8) =4756a(9) =14650a(10) =45065a(11) =138622a(12) =426528a(13) =1312242a(14) =4037155a(15) =12420806a(16) =38213753a(17) =117567880a(18) =361708733a(19) =1112830322a(20) =3423724282a(21) =10533403974a(22) =32406988208a(23) =99703082744a(24) =306745721586a(25) =943731474930