Related to enumeration of edge-rooted catafusenes.

Terms

a(0) =0a(1) =1a(2) =2a(3) =5a(4) =8a(5) =18a(6) =28a(7) =64a(8) =100a(9) =237a(10) =374a(11) =917a(12) =1460a(13) =3679a(14) =5898a(15) =15183a(16) =24468a(17) =64055a(18) =103642a(19) =275011a(20) =446380a(21) =1197616a(22) =1948852a(23) =5277070a(24) =8605288a(25) =23483743a(26) =38362198a(27) =105392983a(28) =172423768a(29) =476459938