a(n) = Sum_{k=1..n} A001263(n,k) * A027656(k).

Terms

a(0) =1a(1) =1a(2) =3a(3) =13a(4) =44a(5) =146a(6) =530a(7) =1975a(8) =7314a(9) =27262a(10) =102802a(11) =390138a(12) =1486064a(13) =5682756a(14) =21812436a(15) =83976075a(16) =324115550a(17) =1253795510a(18) =4859960402a(19) =18871869302a(20) =73398851448a(21) =285882923196