Random walks (binomial transform of A006054).

Terms

a(0) =1a(1) =5a(2) =19a(3) =66a(4) =221a(5) =728a(6) =2380a(7) =7753a(8) =25213a(9) =81927a(10) =266110a(11) =864201a(12) =2806272a(13) =9112264a(14) =29587889a(15) =96072133a(16) =311945595a(17) =1012883066a(18) =3288813893a(19) =10678716664a(20) =34673583028a(21) =112584429049a(22) =365559363741