Number of palstars of length 2n over an alphabet of size 2.

Terms

a(0) =1a(1) =2a(2) =6a(3) =20a(4) =66a(5) =220a(6) =732a(7) =2440a(8) =8134a(9) =27124a(10) =90452a(11) =301656a(12) =1006036a(13) =3355224a(14) =11190040a(15) =37320144a(16) =124467394a(17) =415114844a(18) =1384462172a(19) =4617363016a(20) =15399513116a(21) =51359405064a(22) =171290386824a(23) =571276030192