a(n) = binomial(n+3,3)*binomial(n+6,3).

Terms

a(0) =20a(1) =140a(2) =560a(3) =1680a(4) =4200a(5) =9240a(6) =18480a(7) =34320a(8) =60060a(9) =100100a(10) =160160a(11) =247520a(12) =371280a(13) =542640a(14) =775200a(15) =1085280a(16) =1492260a(17) =2018940a(18) =2691920a(19) =3542000a(20) =4604600a(21) =5920200a(22) =7534800a(23) =9500400a(24) =11875500a(25) =14725620a(26) =18123840a(27) =22151360a(28) =26898080a(29) =32463200