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| n | a(n) |
|---|---|
| 0 | 2 |
| 1 | 2 |
| 2 | 4 |
| 3 | 11 |
| 4 | 36 |
| 5 | 127 |
| 6 | 463 |
| 7 | 1717 |
| 8 | 6436 |
| 9 | 24311 |
| 10 | 92379 |
| 11 | 352717 |
| 12 | 1352079 |
| 13 | 5200301 |
| 14 | 20058301 |
| 15 | 77558761 |
| 16 | 300540196 |
| 17 | 1166803111 |
| 18 | 4537567651 |
| 19 | 17672631901 |
| 20 | 68923264411 |
| 21 | 269128937221 |
| 22 | 1052049481861 |
| 23 | 4116715363801 |
| 24 | 16123801841551 |
| 25 | 63205303218877 |
| 26 | 247959266474053 |
[2,2,4,11,36,127,463,1717,6436,24311,92379,352717, 1352079,5200301,20058301,77558761,300540196, 1166803111,4537567651,17672631901,68923264411, 269128937221,1052049481861,4116715363801, 16123801841551,63205303218877,247959266474053] |