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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 3 |
| 3 | 11 |
| 4 | 38 |
| 5 | 132 |
| 6 | 458 |
| 7 | 1589 |
| 8 | 5513 |
| 9 | 19127 |
| 10 | 66360 |
| 11 | 230232 |
| 12 | 798776 |
| 13 | 2771305 |
| 14 | 9614875 |
| 15 | 33358227 |
| 16 | 115734350 |
| 17 | 401533324 |
| 18 | 1393095570 |
| 19 | 4833260781 |
| 20 | 16768705809 |
| 21 | 58178010095 |
| 22 | 201845085552 |
| 23 | 700289310256 |
| 24 | 2429611385968 |
| 25 | 8429389682769 |
| 26 | 29245257424435 |
| 27 | 101464650942619 |
[0,1,3,11,38,132,458,1589,5513,19127,66360,230232, 798776,2771305,9614875,33358227,115734350, 401533324,1393095570,4833260781,16768705809, 58178010095,201845085552,700289310256, 2429611385968,8429389682769,29245257424435, 101464650942619] |