Column 1 of triangle A107876.

Terms

a(0) =1a(1) =1a(2) =2a(3) =7a(4) =37a(5) =268a(6) =2496a(7) =28612a(8) =391189a(9) =6230646a(10) =113521387a(11) =2332049710a(12) =53384167192