Self-convolution of array T given by A026692.

Terms

a(0) =1a(1) =2a(2) =6a(3) =20a(4) =98a(5) =502a(6) =2126a(7) =8382a(8) =39624a(9) =203562a(10) =922944a(11) =3886840a(12) =18431462a(13) =93930404a(14) =435553556a(15) =1893481706a(16) =9028569112a(17) =45794495192a(18) =214665970468a(19) =950426429104