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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 1 |
| 3 | 1 |
| 4 | 2 |
| 5 | 7 |
| 6 | 30 |
| 7 | 139 |
| 8 | 723 |
| 9 | 4487 |
| 10 | 33551 |
| 11 | 289854 |
| 12 | 2774999 |
| 13 | 29016343 |
| 14 | 333139222 |
| 15 | 4232908176 |
| 16 | 59442337179 |
| 17 | 912948755487 |
| 18 | 15154215501815 |
| 19 | 269933506466203 |
| 20 | 5150440487875190 |
| 21 | 105326085645729766 |
| 22 | 2307425141636199329 |
| 23 | 53998118146846356916 |
| 24 | 1343998910355295080556 |
[1,0,1,1,2,7,30,139,723,4487,33551,289854,2774999, 29016343,333139222,4232908176,59442337179, 912948755487,15154215501815,269933506466203, 5150440487875190,105326085645729766, 2307425141636199329,53998118146846356916, 1343998910355295080556] |