| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 3 |
| 3 | 7 |
| 4 | 25 |
| 5 | 72 |
| 6 | 278 |
| 7 | 916 |
| 8 | 3672 |
| 9 | 12993 |
| 10 | 53655 |
| 11 | 199801 |
| 12 | 841352 |
| 13 | 3247398 |
| 14 | 13885219 |
| 15 | 55084307 |
| 16 | 238324288 |
| 17 | 965836929 |
| 18 | 4218990574 |
| 19 | 17394476665 |
| 20 | 76585028175 |
| 21 | 320237085936 |
| 22 | 1419355904803 |
| 23 | 6005418138172 |
| 24 | 26768693800482 |
| 25 | 114400021806862 |
| 26 | 512438742183608 |
| 27 | 2208901209753286 |
| 28 | 9937017305427740 |
[1,1,3,7,25,72,278,916,3672,12993,53655,199801, 841352,3247398,13885219,55084307,238324288, 965836929,4218990574,17394476665,76585028175, 320237085936,1419355904803,6005418138172, 26768693800482,114400021806862,512438742183608, 2208901209753286,9937017305427740] |