a(n) = 5*(n+1)*binomial(n+4,6).

Terms

a(0) =15a(1) =140a(2) =700a(3) =2520a(4) =7350a(5) =18480a(6) =41580a(7) =85800a(8) =165165a(9) =300300a(10) =520520a(11) =866320a(12) =1392300a(13) =2170560a(14) =3294600a(15) =4883760a(16) =7088235a(17) =10094700a(18) =14132580a(19) =19481000a(20) =26476450a(21) =35521200a(22) =47092500a(23) =61752600a(24) =80159625a(25) =103079340a(26) =131397840a(27) =166135200a(28) =208460120a(29) =259705600