a(n) = 70*(n+1)*binomial(2*n+1,n+1)/(n+5).

Terms

a(0) =14a(1) =70a(2) =300a(3) =1225a(4) =4900a(5) =19404a(6) =76440a(7) =300300a(8) =1178100a(9) =4618900a(10) =18106088a(11) =70984095a(12) =278369000a(13) =1092063000a(14) =4286142000a(15) =16830250920a(16) =66118842900a(17) =259878874500