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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 7 |
| 5 | 22 |
| 6 | 62 |
| 7 | 182 |
| 8 | 583 |
| 9 | 1928 |
| 10 | 6358 |
| 11 | 21063 |
| 12 | 70888 |
| 13 | 241889 |
| 14 | 831634 |
| 15 | 2874584 |
| 16 | 9995579 |
| 17 | 34966279 |
| 18 | 122938956 |
| 19 | 434062141 |
| 20 | 1538378816 |
| 21 | 5471697241 |
| 22 | 19525345791 |
| 23 | 69880082323 |
| 24 | 250767909528 |
| 25 | 902123110483 |
| 26 | 3252793321513 |
| 27 | 11753570922933 |
| 28 | 42553831219830 |
[1,1,1,2,7,22,62,182,583,1928,6358,21063,70888, 241889,831634,2874584,9995579,34966279,122938956, 434062141,1538378816,5471697241,19525345791, 69880082323,250767909528,902123110483, 3252793321513,11753570922933,42553831219830] |