171481domain: NPropertiesPrimalityPrimeyesAppears in sequencesa(0)=1, for n>=1 a(n) = Sum_{k=0..n} 5^k*N(n,k) where N(n,k) = C(n,k)*C(n,k+1)/n are the Narayana numbers (A001263).at n=7A078009a(n) = N(7,n), where N(7,x) is the 7th Narayana polynomial.at n=5A090200Series reversion of x/(1+6x+5x^2).at n=7A127848Prime numbersat n=15622