Number of h- and H-steps at level 0 in all lattice paths in B(n).

Terms

a(0) =0a(1) =1a(2) =3a(3) =7a(4) =17a(5) =40a(6) =94a(7) =222a(8) =526a(9) =1252a(10) =2994a(11) =7191a(12) =17343a(13) =41989a(14) =102023a(15) =248712a(16) =608168a(17) =1491349a(18) =3666685a(19) =9037003a(20) =22323243a(21) =55259206a(22) =137058248a(23) =340567477a(24) =847711177a(25) =2113455657a(26) =5277115687a(27) =13195311961a(28) =33038994039a(29) =82829585094