a(n) = Sum_{i=1..n} C(i+6,7)^2.

Terms

a(0) =1a(1) =65a(2) =1361a(3) =15761a(4) =124661a(5) =751925a(6) =3696581a(7) =15475205a(8) =56884430a(9) =187758030a(10) =565982734a(11) =1578749710a(12) =4117700254a(13) =10127050654a(14) =23648089054a(15) =52733344990a(16) =112835299639a(17) =232623278455a(18) =463695768455a(19) =896396608455