A136731 Column 1 of square array A136730.
1, 2, 5, 23, 175, 1935, 28432, 523290, 11587072, 299942890, 8886126540, 296438370794, 10993731095695, 448604373236731, 19971257117211555, 963142501803505255, 50015707804752012825, 2782336529985704607295
Offset: 0