Principal diagonal of the convolution array A213571.

Terms

a(0) =1a(1) =13a(2) =82a(3) =406a(4) =1809a(5) =7659a(6) =31588a(7) =128476a(8) =518611a(9) =2084809a(10) =8361918a(11) =33497010a(12) =134094757a(13) =536608663a(14) =2146926472a(15) =8588754808a(16) =34357247847a(17) =137433710421a(18) =549744803650