Row 2 of rectangular table A124530.

Terms

a(0) =1a(1) =1a(2) =3a(3) =10a(4) =39a(5) =174a(6) =858a(7) =4564a(8) =25793a(9) =153301a(10) =951325a(11) =6130757a(12) =40861658a(13) =280767621a(14) =1983859580a(15) =14385651988a(16) =106878699675a(17) =812480791324