Related to enumeration of edge-rooted catafusenes.

Terms

a(0) =0a(1) =0a(2) =0a(3) =1a(4) =2a(5) =8a(6) =14a(7) =43a(8) =72a(9) =204a(10) =336a(11) =926a(12) =1516a(13) =4144a(14) =6772a(15) =18504a(16) =30236a(17) =82844a(18) =135452a(19) =372581a(20) =609710a(21) =1684220a(22) =2758730a(23) =7652531a(24) =12546332a(25) =34941752a(26) =57337172a(27) =160280987a(28) =263224802a(29) =738363872