Nearest integer to Gamma(n+1/2).

Terms

a(0) =2a(1) =1a(2) =1a(3) =3a(4) =12a(5) =52a(6) =288a(7) =1871a(8) =14034a(9) =119292a(10) =1133278a(11) =11899423a(12) =136843365a(13) =1710542068a(14) =23092317922a(15) =334838609874