A120896 Central terms of triangle A120894 (cascadence of 1+x+x^2).

1, 1, 2, 5, 10, 27, 73, 189, 518, 1413, 3857, 10707, 29804, 83365, 234665, 662654, 1878059, 5341302, 15231940, 43552610, 124829236, 358537455, 1031835260, 2974872009, 8590929683, 24847042484, 71964879243, 208704926659