a(n) = A120963(2*n+1)/2.

Terms

a(0) =1a(1) =5a(2) =19a(3) =59a(4) =165a(5) =419a(6) =1001a(7) =2257a(8) =4877a(9) =10133a(10) =20399a(11) =39881a(12) =76085a(13) =141877a(14) =259373a(15) =465493a(16) =821813a(17) =1428725a(18) =2449573a(19) =4145249a(20) =6931259a(21) =11459483a(22) =18749007a(23) =30373189a(24) =48752125a(25) =77568683a(26) =122406223a(27) =191651957a(28) =297856813a(29) =459652759