Third column of triangle A054453.

Terms

a(0) =1a(1) =2a(2) =6a(3) =12a(4) =26a(5) =50a(6) =97a(7) =180a(8) =332a(9) =600a(10) =1076a(11) =1908a(12) =3361a(13) =5878a(14) =10226a(15) =17700a(16) =30510a(17) =52390a(18) =89665a(19) =153000a(20) =260376a(21) =442032a(22) =748776a(23) =1265832a(24) =2136001a(25) =3598250a(26) =6052062a(27) =10164540a(28) =17048642