Self-convolution of array T given by A026681.

Terms

a(0) =1a(1) =2a(2) =11a(3) =52a(4) =200a(5) =742a(6) =3532a(7) =18216a(8) =80728a(9) =331320a(10) =1567106a(11) =8014124a(12) =36841482a(13) =158071146a(14) =751787936a(15) =3820895710a(16) =17829567326a(17) =78319157796a(18) =374296581082