A018034 Powers of cube root of 20 rounded to nearest integer.

1, 3, 7, 20, 54, 147, 400, 1086, 2947, 8000, 21715, 58945, 160000, 434307, 1178890, 3200000, 8686136, 23577802, 64000000, 173722727, 471556032, 1280000000, 3474454549, 9431120637, 25600000000