a(n) = A027052(n, 2n-8).

Terms

a(0) =1a(1) =1a(2) =3a(3) =11a(4) =37a(5) =125a(6) =421a(7) =1405a(8) =4637a(9) =15125a(10) =48777a(11) =155665a(12) =492157a(13) =1543269a(14) =4804663a(15) =14865495a(16) =45745953a(17) =140118817a(18) =427445507a(19) =1299383403a(20) =3937901525a(21) =11902380845a(22) =35891429675a(23) =108009437323a(24) =324455779889a(25) =973119941425