Row 1 of rectangular table A124530.

Terms

a(0) =1a(1) =1a(2) =2a(3) =5a(4) =16a(5) =62a(6) =274a(7) =1332a(8) =6978a(9) =38873a(10) =228090a(11) =1399625a(12) =8933506a(13) =59066261a(14) =403241292a(15) =2835267821a(16) =20490128048a(17) =151951503074