Erroneous version of A006758.

Terms

a(0) =0a(1) =0a(2) =1a(3) =6a(4) =17a(5) =59a(6) =195a(7) =703a(8) =2499a(9) =9188a(10) =33890a(11) =126758a(12) =476269a(13) =1802311a(14) =6849776a(15) =26152417a(16) =100203193