The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 2 |
| 3 | 3 |
| 4 | 12 |
| 5 | 18 |
| 6 | 23 |
| 7 | 57 |
| 8 | 128 |
| 9 | 543 |
| 10 | 584 |
| 11 | 833 |
| 12 | 2450 |
| 13 | 2810 |
| 14 | 2873 |
| 15 | 3671 |
| 16 | 6384 |
| 17 | 10296 |
| 18 | 16704 |
| 19 | 53049 |
| 20 | 56544 |
| 21 | 74253 |
[0,2,3,12,18,23,57,128,543,584,833,2450,2810,2873, 3671,6384,10296,16704,53049,56544,74253] |