a(n) = T(2n+3,n), array T as in A055818.

Terms

a(0) =1a(1) =23a(2) =144a(3) =848a(4) =4880a(5) =27816a(6) =157920a(7) =895264a(8) =5074272a(9) =28772280a(10) =163262704a(11) =927203184a(12) =5270629104a(13) =29988361032a(14) =170780080320a(15) =973422085184