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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 2 |
| 3 | 7 |
| 4 | 34 |
| 5 | 171 |
| 6 | 905 |
| 7 | 4952 |
| 8 | 27802 |
| 9 | 159254 |
| 10 | 927081 |
| 11 | 5468960 |
| 12 | 32621669 |
| 13 | 196422509 |
| 14 | 1192294778 |
| 15 | 7288208927 |
| 16 | 44825586130 |
| 17 | 277196752569 |
| 18 | 1722454028174 |
| 19 | 10749430579118 |
| 20 | 67346519863117 |
| 21 | 423425225290485 |
| 22 | 2670741276559282 |
| 23 | 16895070479910967 |
| 24 | 107165705513319749 |
| 25 | 681438064187707596 |
[1,0,2,7,34,171,905,4952,27802,159254,927081, 5468960,32621669,196422509,1192294778,7288208927, 44825586130,277196752569,1722454028174, 10749430579118,67346519863117,423425225290485, 2670741276559282,16895070479910967, 107165705513319749,681438064187707596] |