1553940domain: NAppears in sequencesa(n) = T(n,n), T given by A026552. Also a(n) is the number of integer strings s(0),...,s(n) counted by T, such that s(n)=0.at n=18A026553a(n) = self-convolution of row n of array T given by A026519.at n=9A027262Self-convolution of row n of array T given by A026552.at n=9A027272