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| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 1 |
| 4 | 3 |
| 5 | 20 |
| 6 | 42 |
| 7 | 151 |
| 8 | 265 |
| 9 | 753 |
| 10 | 3006 |
| 11 | 4594 |
| 12 | 15117 |
| 13 | 31576 |
| 14 | 45002 |
| 15 | 89125 |
| 16 | 235501 |
| 17 | 589613 |
| 18 | 792426 |
| 19 | 1871442 |
| 20 | 3251293 |
| 21 | 4261819 |
| 22 | 9403682 |
| 23 | 15690192 |
| 24 | 33111688 |
| 25 | 86520382 |
| 26 | 137957345 |
| 27 | 173655404 |
| 28 | 273492399 |
| 29 | 342231447 |
| 30 | 532915031 |
| 31 | 2380864800 |
| 32 | 3601147053 |
| 33 | 6628703864 |
[0,0,1,3,20,42,151,265,753,3006,4594,15117,31576, 45002,89125,235501,589613,792426,1871442,3251293, 4261819,9403682,15690192,33111688,86520382, 137957345,173655404,273492399,342231447,532915031, 2380864800,3601147053,6628703864] |