Binomial coefficient C(2n,n-4).

Terms

a(0) =1a(1) =10a(2) =66a(3) =364a(4) =1820a(5) =8568a(6) =38760a(7) =170544a(8) =735471a(9) =3124550a(10) =13123110a(11) =54627300a(12) =225792840a(13) =927983760a(14) =3796297200a(15) =15471286560a(16) =62852101650a(17) =254661927156