Partial sums of A247287.

Terms

a(0) =0a(1) =0a(2) =1a(3) =5a(4) =18a(5) =56a(6) =164a(7) =468a(8) =1325a(9) =3751a(10) =10653a(11) =30381a(12) =87003a(13) =250095a(14) =721300a(15) =2086308a(16) =6049629a(17) =17580415a(18) =51187605a(19) =149293221a(20) =436088521a(21) =1275559185a(22) =3735597612a(23) =10952250100a(24) =32143070778a(25) =94422309606a(26) =277608161509a(27) =816829091513