a(n) = T(n, 2*n-10), T given by A027926.

Terms

a(0) =1a(1) =2a(2) =5a(3) =13a(4) =34a(5) =89a(6) =232a(7) =596a(8) =1490a(9) =3588a(10) =8273a(11) =18228a(12) =38403a(13) =77533a(14) =150438a(15) =281403a(16) =509015a(17) =892926a(18) =1523117a(19) =2532359a(20) =4112704a(21) =6536993a(22) =10186540a(23) =15586342a(24) =23449376a(25) =34731776a(26) =50700937a(27) =73018870a(28) =103843433a(29) =145950389