Central terms of triangle A110440.

Terms

a(0) =1a(1) =6a(2) =60a(3) =684a(4) =8270a(5) =103356a(6) =1319318a(7) =17089176a(8) =223742646a(9) =2953453860a(10) =39238422432a(11) =524028551976