Self-convolution of array T given by A026615.

Terms

a(0) =1a(1) =2a(2) =11a(3) =52a(4) =200a(5) =742a(6) =2752a(7) =10278a(8) =38670a(9) =146426a(10) =557408a(11) =2131318a(12) =8179646a(13) =31491202a(14) =121568150a(15) =470404274a(16) =1823968074a(17) =7085220834a(18) =27567196704a(19) =107414120214a(20) =419080195374