A077836 Expansion of (1-x)/(1-3*x-3*x^2-3*x^3).

1, 2, 9, 36, 141, 558, 2205, 8712, 34425, 136026, 537489, 2123820, 8392005, 33159942, 131027301, 517737744, 2045774961, 8083620018, 31941398169, 126212379444, 498712192893, 1970597911518, 7786567451565, 30767632667928, 121574394093033, 480385782637578