1174985domain: NAppears in sequencesSum C(n-3k,3k+1), k=0..floor(n/6).at n=31A102516a(n) = Sum_{k=0..floor(n/3)} binomial(n+3*k,n-3*k).at n=16A373905Expansion of (1 + x)/(1 - x^3*(1 + x)^3).at n=31A375319