12184181domain: NAppears in sequencesa(n) = Sum_{k=0..floor(n/3)} binomial(2*n-5*k,k).at n=34A373639a(n) = Sum_{k=0..floor(n/2)} binomial(3*n-5*k-1,k).at n=23A373653Number of compositions of 6*n-4 into parts 1 and 6.at n=11A373959