Logarithmic numbers.

Terms

a(0) =0a(1) =1a(2) =3a(3) =8a(4) =24a(5) =89a(6) =415a(7) =2372a(8) =16072a(9) =125673a(10) =1112083a(11) =10976184a(12) =119481296a(13) =1421542641a(14) =18348340127a(15) =255323504932