47082494816domain: NAppears in sequencesa(n) = T(n, n-3), T given by A026552. Also a(n) = number of integer strings s(0), ..., s(n) counted by T, such that s(n) = 3.at n=27A026556a(n) = Sum_{k=0..2n-3} T(n,k) * T(n,k+3), with T given by A026519.at n=12A027265a(n) = Sum_{k=0..2n-3} T(n,k) * T(n,k+3), with T given by A026552.at n=12A027275