Sum along upward diagonal of Pascal triangle to center.

Terms

a(0) =1a(1) =1a(2) =1a(3) =3a(4) =4a(5) =5a(6) =12a(7) =17a(8) =23a(9) =50a(10) =73a(11) =103a(12) =211a(13) =314a(14) =455a(15) =895a(16) =1350a(17) =1993a(18) =3805a(19) =5798a(20) =8679a(21) =16193a(22) =24872a(23) =37633a(24) =68940a(25) =106573a(26) =162643a(27) =293526a(28) =456169a(29) =701075