a(n) = A241477(n, n).

Terms

a(0) =1a(1) =1a(2) =2a(3) =2a(4) =2a(5) =6a(6) =4a(7) =20a(8) =10a(9) =70a(10) =28a(11) =252a(12) =84a(13) =924a(14) =264a(15) =3432a(16) =858a(17) =12870a(18) =2860a(19) =48620a(20) =9724a(21) =184756a(22) =33592a(23) =705432a(24) =117572a(25) =2704156a(26) =416024a(27) =10400600a(28) =1485800a(29) =40116600