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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 5 |
| 3 | 15 |
| 4 | 50 |
| 5 | 176 |
| 6 | 638 |
| 7 | 2351 |
| 8 | 8735 |
| 9 | 32523 |
| 10 | 120707 |
| 11 | 444218 |
| 12 | 1611211 |
| 13 | 5714056 |
| 14 | 19578953 |
| 15 | 63495983 |
| 16 | 186784641 |
| 17 | 442718804 |
| 18 | 396470087 |
| 19 | -4588483661 |
| 20 | -45923198497 |
| 21 | -305945783479 |
| 22 | -1761810468901 |
| 23 | -9395726622973 |
| 24 | -47743575327196 |
| 25 | -234512941253088 |
| 26 | -1122653095777562 |
[1,2,5,15,50,176,638,2351,8735,32523,120707, 444218,1611211,5714056,19578953,63495983, 186784641,442718804,396470087,-4588483661, -45923198497,-305945783479,-1761810468901, -9395726622973,-47743575327196,-234512941253088, -1122653095777562] |