387739domain: NAppears in sequencesa(n) = Sum_{k=0..n} 6^k*N(n,k), with a(0)=1, where N(n,k) = C(n,k) * C(n,k+1)/n are the Narayana numbers (A001263).at n=7A078018a(n) = N(7,n), where N(7,x) is the 7th Narayana polynomial.at n=6A090200a(n) = (1/n) * Sum_{k=0..n-1} C(n,k) * C(n,k+1) * (n-1)^k.at n=6A099169