a(n) = n*(n+5)*(n+6)*(n+7)/24.

Terms

a(0) =0a(1) =14a(2) =42a(3) =90a(4) =165a(5) =275a(6) =429a(7) =637a(8) =910a(9) =1260a(10) =1700a(11) =2244a(12) =2907a(13) =3705a(14) =4655a(15) =5775a(16) =7084a(17) =8602a(18) =10350a(19) =12350a(20) =14625a(21) =17199a(22) =20097a(23) =23345a(24) =26970a(25) =31000a(26) =35464a(27) =40392a(28) =45815a(29) =51765