A diagonal of A008296.

Terms

a(0) =-1a(1) =-1a(2) =5a(3) =25a(4) =70a(5) =154a(6) =294a(7) =510a(8) =825a(9) =1265a(10) =1859a(11) =2639a(12) =3640a(13) =4900a(14) =6460a(15) =8364a(16) =10659a(17) =13395a(18) =16625a(19) =20405a(20) =24794a(21) =29854a(22) =35650a(23) =42250a(24) =49725a(25) =58149a(26) =67599a(27) =78155a(28) =89900a(29) =102920