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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 2 |
| 3 | 10 |
| 4 | 53 |
| 5 | 269 |
| 6 | 1378 |
| 7 | 7057 |
| 8 | 36152 |
| 9 | 185192 |
| 10 | 948664 |
| 11 | 4859596 |
| 12 | 24893585 |
| 13 | 127518875 |
| 14 | 653222944 |
| 15 | 3346172776 |
| 16 | 17140965623 |
| 17 | 87805597652 |
| 18 | 449789301892 |
| 19 | 2304071965189 |
| 20 | 11802743188937 |
| 21 | 60460241206049 |
| 22 | 309711116141929 |
| 23 | 1586513277940591 |
[0,2,10,53,269,1378,7057,36152,185192,948664, 4859596,24893585,127518875,653222944,3346172776, 17140965623,87805597652,449789301892, 2304071965189,11802743188937,60460241206049, 309711116141929,1586513277940591] |