Number of collections of nonempty multisets with a total of n objects of exactly two colors.

Terms

a(0) =2a(1) =8a(2) =23a(3) =56a(4) =127a(5) =268a(6) =547a(7) =1072a(8) =2055a(9) =3836a(10) =7045a(11) =12692a(12) =22566a(13) =39542a(14) =68520a(15) =117354a(16) =199082a(17) =334446a(18) =557175a(19) =920528a(20) =1509606a(21) =2457698a(22) =3974813a(23) =6387026a(24) =10201990a(25) =16201424a(26) =25589505a(27) =40205766a(28) =62857564a(29) =97800674