a(n) = Lucas(4*n+2) + 3, or Lucas(2*n)*Lucas(2*n+2).

A081077

a(n) = Lucas(4*n+2) + 3, or Lucas(2*n)*Lucas(2*n+2).

Terms

    a(0) =6a(1) =21a(2) =126a(3) =846a(4) =5781a(5) =39606a(6) =271446a(7) =1860501a(8) =12752046a(9) =87403806a(10) =599074581a(11) =4106118246a(12) =28143753126a(13) =192900153621

External references