Row 2 of table A128325.

Terms

a(0) =1a(1) =1a(2) =4a(3) =20a(4) =114a(5) =712a(6) =4772a(7) =33896a(8) =253102a(9) =1975610a(10) =16054568a(11) =135413280a(12) =1182664740a(13) =10675334958a(14) =99437919664a(15) =954581258020