55108565584domain: NAppears in sequencesa(n) = T(n,n-1), T given by A026552. Also a(n) is the number of integer strings s(0),...,s(n) counted by T, such that s(n)=1.at n=29A026554a(n) = Sum_{k=0..2n-1} T(n,k) * T(n,k+1), with T given by A026519.at n=14A027263a(n) = Sum_{k=0..2n-1} T(n,k) * T(n,k+1), with T given by A026552.at n=14A027273