a(n) = binomial(n+6,5) - binomial(n,5).

Terms

a(0) =6a(1) =21a(2) =56a(3) =126a(4) =252a(5) =461a(6) =786a(7) =1266a(8) =1946a(9) =2877a(10) =4116a(11) =5726a(12) =7776a(13) =10341a(14) =13502a(15) =17346a(16) =21966a(17) =27461a(18) =33936a(19) =41502a(20) =50276a(21) =60381a(22) =71946a(23) =85106a(24) =100002a(25) =116781a(26) =135596a(27) =156606a(28) =179976a(29) =205877