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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 3 |
| 5 | 11 |
| 6 | 26 |
| 7 | 50 |
| 8 | 315 |
| 9 | 1168 |
| 10 | 3309 |
| 11 | 7910 |
| 12 | 78134 |
| 13 | 431354 |
| 14 | 1748956 |
| 15 | 5797168 |
| 16 | 16619603 |
| 17 | 239887424 |
| 18 | 1875375485 |
| 19 | 10496708022 |
| 20 | 47013492080 |
| 21 | 178807998112 |
| 22 | 599025922320 |
| 23 | 11965846097382 |
| 24 | 126883998286089 |
| 25 | 947079890934441 |
| 26 | 5574231845278396 |
| 27 | 27500583638094490 |
[1,1,1,2,3,11,26,50,315,1168,3309,7910,78134, 431354,1748956,5797168,16619603,239887424, 1875375485,10496708022,47013492080,178807998112, 599025922320,11965846097382,126883998286089, 947079890934441,5574231845278396, 27500583638094490] |