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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 7 |
| 3 | 23 |
| 4 | 96 |
| 5 | 370 |
| 6 | 1566 |
| 7 | 6489 |
| 8 | 28076 |
| 9 | 121360 |
| 10 | 532628 |
| 11 | 2351022 |
| 12 | 10460730 |
| 13 | 46813510 |
| 14 | 210658107 |
| 15 | 951491883 |
| 16 | 4316746000 |
| 17 | 19642710584 |
| 18 | 89689252555 |
| 19 | 410604172754 |
| 20 | 1884310038732 |
| 21 | 8667443235220 |
| 22 | 39945921903911 |
| 23 | 184461876354657 |
| 24 | 853252405659431 |
| 25 | 3952900305874812 |
| 26 | 18340232241154683 |
| 27 | 85204091647976402 |
[1,2,7,23,96,370,1566,6489,28076,121360,532628, 2351022,10460730,46813510,210658107,951491883, 4316746000,19642710584,89689252555,410604172754, 1884310038732,8667443235220,39945921903911, 184461876354657,853252405659431,3952900305874812, 18340232241154683,85204091647976402] |