a(n) = Sum_{i=1..n} C(i+2,3)^3.

Terms

a(0) =1a(1) =65a(2) =1065a(3) =9065a(4) =51940a(5) =227556a(6) =820260a(7) =2548260a(8) =7040385a(9) =17688385a(10) =41082041a(11) =89310585a(12) =183506960a(13) =359122960a(14) =673554960a(15) =1216893456a(16) =2126746665a(17) =3608290665a(18) =5960927665a(19) =9613191665a(20) =15167828676a(21) =23459298500a(22) =35626298500a(23) =53202298500a(24) =78227501625a(25) =113386110201