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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 2 |
| 3 | 5 |
| 4 | 28 |
| 5 | 201 |
| 6 | 1566 |
| 7 | 14349 |
| 8 | 154456 |
| 9 | 1870225 |
| 10 | 25034650 |
| 11 | 368887573 |
| 12 | 5938767924 |
| 13 | 103580577881 |
| 14 | 1945112687350 |
| 15 | 39137964503837 |
| 16 | 840076566197552 |
| 17 | 19158967944112929 |
| 18 | 462642378426338994 |
| 19 | 11792392190823752229 |
[0,1,2,5,28,201,1566,14349,154456,1870225, 25034650,368887573,5938767924,103580577881, 1945112687350,39137964503837,840076566197552, 19158967944112929,462642378426338994, 11792392190823752229] |