a(n) = A081038(n) + A077616(n).

Terms

a(0) =6a(1) =31a(2) =144a(3) =621a(4) =2538a(5) =9963a(6) =37908a(7) =140697a(8) =511758a(9) =1830519a(10) =6456024a(11) =22497669a(12) =77590386a(13) =265189059a(14) =899198172a(15) =3027619377a(16) =10130328342a(17) =33705582543a(18) =111577100832a(19) =367662044061