3041899638domain: NAppears in sequencesa(n) = Sum_{k=0..n} binomial(5*k,n-k).at n=18A360090Number of compositions of 6*n into parts 1 and 6.at n=15A371125a(n) = Sum_{k=0..floor(n/2)} binomial(3*n-5*k,k).at n=30A373638