297940domain: NAppears in sequencesa(n) = Sum_{k=0..2n-3} T(n,k) * T(n,k+3), with T given by A026552.at n=5A027275a(n) = Sum_{k=0..m-3} T(n,k) * T(n,k+2), where m=n for n=0,1,2,3; m=2n for n >= 4; and T is given by A026082.at n=5A027318