a(n) = A027113(n, 2n-10).

Terms

a(0) =1a(1) =2a(2) =7a(3) =24a(4) =81a(5) =274a(6) =927a(7) =3132a(8) =10552a(9) =35395a(10) =118065a(11) =391320a(12) =1288260a(13) =4212091a(14) =13679558a(15) =44141377a(16) =141571286a(17) =451475589a(18) =1432198967a(19) =4521270066a(20) =14209424215a(21) =44474645476a(22) =138681426899a(23) =430955113144