a(n) = Sum_{i=0..floor(n/2)} T(2i,n-2i), array T as in A049735.

Terms

a(0) =1a(1) =5a(2) =26a(3) =50a(4) =123a(5) =183a(6) =364a(7) =448a(8) =753a(9) =925a(10) =1414a(11) =1618a(12) =2271a(13) =2599a(14) =3536a(15) =3940a(16) =5133a(17) =5645a(18) =7178a(19) =7822a(20) =9747a(21) =10443a(22) =12780a(23) =13656a(24) =16325a(25) =17413a(26) =20638a(27) =21870a(28) =25531a(29) =26955