The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 4 |
| 3 | 6 |
| 4 | 9 |
| 5 | 12 |
| 6 | 18 |
| 7 | 23 |
| 8 | 28 |
| 9 | 34 |
| 10 | 42 |
| 11 | 49 |
| 12 | 61 |
| 13 | 68 |
| 14 | 80 |
| 15 | 91 |
| 16 | 103 |
| 17 | 111 |
| 18 | 128 |
| 19 | 138 |
| 20 | 156 |
[1,2,4,6,9,12,18,23,28,34,42,49,61,68,80,91,103, 111,128,138,156] |