Duplicate of A083789.

Terms

a(0) =1a(1) =2a(2) =6a(3) =9a(4) =12a(5) =28a(6) =30a(7) =1811a(8) =1976a(9) =8384a(10) =53760a(11) =243875a(12) =639336a(13) =41381633a(14) =102621357