Column 3 of A142249.

Terms

a(0) =3a(1) =19a(2) =80a(3) =286a(4) =945a(5) =2997a(6) =9294a(7) =28456a(8) =86471a(9) =261559a(10) =788892a(11) =2375010a(12) =7141581a(13) =21457705a(14) =64438874a(15) =193447948a(16) =580606275a(17) =1742343435a(18) =5228079240a(19) =15686335270a(20) =47063200553a(21) =141197990749a(22) =423610749990