110056domain: NAppears in sequencesa(n) = Sum_{k=0..6} binomial(n,k).at n=22A008859Race of lucky numbers of the form 4*k - 1 vs. 4*k + 1 is tied at the a(n)-th lucky number.at n=18A330359a(n) = Sum_{k=0..n} binomial(4*n-2,k).at n=6A387036