a(n) = n*(Lucas(n)*Lucas(n+1) - 2).

Terms

a(0) =0a(1) =1a(2) =20a(3) =78a(4) =300a(5) =980a(6) =3120a(7) =9527a(8) =28560a(9) =84114a(10) =244750a(11) =704836a(12) =2013120a(13) =5709613a(14) =16097900a(15) =45155190a(16) =126099120a(17) =350765012a(18) =972333360a(19) =2687024099a(20) =7404969000a(21) =20355783546a(22) =55829853970a(23) =152808294148a(24) =417451104000