Row sums of A258307.

Terms

a(0) =1a(1) =1a(2) =3a(3) =7a(4) =24a(5) =74a(6) =277a(7) =997a(8) =4016a(9) =16029a(10) =68802a(11) =296740a(12) =1347175a(13) =6185975a(14) =29530010a(15) =143008050a(16) =714469780a(17) =3625572745a(18) =18884279461a(19) =99936069760a(20) =540947985741