a(n) = n * A056219(n+1).

Terms

a(0) =2a(1) =4a(2) =12a(3) =20a(4) =30a(5) =54a(6) =91a(7) =120a(8) =171a(9) =250a(10) =374a(11) =504a(12) =663a(13) =854a(14) =1170a(15) =1568a(16) =2074a(17) =2628a(18) =3325a(19) =4180a(20) =5313a(21) =6754a(22) =8602a(23) =10656a(24) =13100a(25) =16042a(26) =19683a(27) =24024a(28) =29464a(29) =36000