a(n) = 26*(n+1)*binomial(n+3,13).

Terms

a(0) =286a(1) =4368a(2) =35490a(3) =203840a(4) =928200a(5) =3564288a(6) =11992344a(7) =36279360a(8) =100524060a(9) =258658400a(10) =624660036a(11) =1427794368a(12) =3109779400a(13) =6489974400a(14) =13037895000a(15) =25310900160a(16) =47640468330a(17) =87185170800a(18) =155514818550a(19) =270951408000a(20) =461972150640a(21) =772082488320