G.f.: 3F2([1/9, 4/9, 7/9], [2/3, 1], 729 x).A275453G.f.: 3F2([1/9, 4/9, 7/9], [2/3, 1], 729 x).Terms a(0) =1a(1) =42a(2) =13104a(3) =5705700a(4) =2870226450External referencesoeis: A275453