a(n) = A144066(n+3,3).

Terms

a(0) =1a(1) =60a(2) =490a(3) =2220a(4) =7315a(5) =19656a(6) =45780a(7) =95880a(8) =184965a(9) =334180a(10) =572286a(11) =937300a(12) =1478295a(13) =2257360a(14) =3351720a(15) =4856016a(16) =6884745a(17) =9574860a(18) =13088530a(19) =17616060a(20) =23378971a(21) =30633240a(22) =39672700a(23) =50832600a(24) =64493325a(25) =81084276a(26) =101087910