A018106 Powers of fourth root of 21 rounded to nearest integer.

1, 2, 5, 10, 21, 45, 96, 206, 441, 944, 2021, 4326, 9261, 19825, 42439, 90849, 194481, 416325, 891224, 1907839, 4084101, 8742815, 18715702, 40064612, 85766121, 183599119, 393029742, 841356859, 1801088541