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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 2 |
| 3 | 7 |
| 4 | 25 |
| 5 | 96 |
| 6 | 382 |
| 7 | 1567 |
| 8 | 6575 |
| 9 | 28096 |
| 10 | 121847 |
| 11 | 534953 |
| 12 | 2373032 |
| 13 | 10619922 |
| 14 | 47890013 |
| 15 | 217395690 |
| 16 | 992640367 |
| 17 | 4555957948 |
| 18 | 21007405327 |
| 19 | 97266928685 |
| 20 | 452046424465 |
| 21 | 2108022305795 |
| 22 | 9860773604035 |
| 23 | 46256877824220 |
| 24 | 217555982625385 |
| 25 | 1025667805621986 |
| 26 | 4846240583558277 |
[0,1,2,7,25,96,382,1567,6575,28096,121847,534953, 2373032,10619922,47890013,217395690,992640367, 4555957948,21007405327,97266928685,452046424465, 2108022305795,9860773604035,46256877824220, 217555982625385,1025667805621986,4846240583558277] |