In A250544, A223069, A250669, A250692 R. H. Hardin gives the empirical recurrence a(n) = 16*a(n-1)-106*a(n-2)+376*a(n-3)-769*a(n-4) +904*a(n-5)-564*a(n-6)+144*a(n-7) I simply wish to observe that these coefficients are listed in the ninth row of Peter Bala's A246117. Peter