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| n | a(n) |
|---|---|
| 2 | 1 |
| 3 | 4 |
| 4 | 10 |
| 5 | 28 |
| 6 | 76 |
| 7 | 209 |
| 8 | 575 |
| 9 | 1589 |
| 10 | 4405 |
| 11 | 12253 |
| 12 | 34189 |
| 13 | 95679 |
| 14 | 268503 |
| 15 | 755457 |
| 16 | 2130717 |
| 17 | 6023235 |
| 18 | 17063139 |
| 19 | 48434514 |
| 20 | 137741280 |
| 21 | 392407134 |
| 22 | 1119766942 |
| 23 | 3200326627 |
| 24 | 9160055809 |
| 25 | 26254474379 |
| 26 | 75348899051 |
| 27 | 216515177336 |
| 28 | 622887159274 |
[1,4,10,28,76,209,575,1589,4405,12253,34189,95679, 268503,755457,2130717,6023235,17063139,48434514, 137741280,392407134,1119766942,3200326627, 9160055809,26254474379,75348899051,216515177336, 622887159274] |