The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 4 |
| 3 | 17 |
| 4 | 69 |
| 5 | 276 |
| 6 | 1105 |
| 7 | 4421 |
| 8 | 17684 |
| 9 | 70737 |
| 10 | 282949 |
| 11 | 1131796 |
| 12 | 4527185 |
| 13 | 18108741 |
| 14 | 72434964 |
| 15 | 289739857 |
| 16 | 1158959429 |
| 17 | 4635837716 |
| 18 | 18543350865 |
| 19 | 74173403461 |
| 20 | 296693613844 |
| 21 | 1186774455377 |
| 22 | 4747097821509 |
| 23 | 18988391286036 |
| 24 | 75953565144145 |
[1,4,17,69,276,1105,4421,17684,70737,282949, 1131796,4527185,18108741,72434964,289739857, 1158959429,4635837716,18543350865,74173403461, 296693613844,1186774455377,4747097821509, 18988391286036,75953565144145] |