a(n) = A000994(n+2) - A000995(n+2).

Terms

a(0) =1a(1) =0a(2) =0a(3) =1a(4) =3a(5) =7a(6) =19a(7) =64a(8) =236a(9) =893a(10) =3489a(11) =14347a(12) =62429a(13) =285580a(14) =1362372a(15) =6749337a(16) =34683211a(17) =184774851a(18) =1019351071a(19) =5813020060a(20) =34206071992a(21) =207391313189