a(n) = (4*n+1)*(4*n+2) = (4*n+2)!/(4*n)!.

Terms

a(0) =2a(1) =30a(2) =90a(3) =182a(4) =306a(5) =462a(6) =650a(7) =870a(8) =1122a(9) =1406a(10) =1722a(11) =2070a(12) =2450a(13) =2862a(14) =3306a(15) =3782a(16) =4290a(17) =4830a(18) =5402a(19) =6006a(20) =6642a(21) =7310a(22) =8010a(23) =8742a(24) =9506a(25) =10302a(26) =11130a(27) =11990a(28) =12882a(29) =13806