a(n) = (n+1)*binomial(n+1,14).

Terms

a(0) =14a(1) =225a(2) =1920a(3) =11560a(4) =55080a(5) =220932a(6) =775200a(7) =2441880a(8) =7034940a(9) =18795370a(10) =47070144a(11) =111435000a(12) =251100200a(13) =541574100a(14) =1123264800a(15) =2249204040a(16) =4362680250a(17) =8220658275a(18) =15085939200a(19) =27020703600a(20) =47327171760a(21) =81198579000a(22) =136666699200a(23) =225962211600a(24) =367443055800