Duplicate of A068804.

Terms

a(0) =1a(1) =3a(2) =6a(3) =10a(4) =21a(5) =45a(6) =78a(7) =120a(8) =190a(9) =210a(10) =231a(11) =435a(12) =465a(13) =9180a(14) =9870a(15) =12403a(16) =24310a(17) =24531