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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 5 |
| 4 | 16 |
| 5 | 57 |
| 6 | 224 |
| 7 | 934 |
| 8 | 4092 |
| 9 | 18581 |
| 10 | 86888 |
| 11 | 415856 |
| 12 | 2029160 |
| 13 | 10061161 |
| 14 | 50568680 |
| 15 | 257129888 |
| 16 | 1320619176 |
| 17 | 6842177174 |
| 18 | 35722456976 |
| 19 | 187772944964 |
| 20 | 992991472328 |
| 21 | 5279633960181 |
| 22 | 28208037066528 |
| 23 | 151373637844440 |
| 24 | 815568695756496 |
| 25 | 4410124252008112 |
[1,1,2,5,16,57,224,934,4092,18581,86888,415856, 2029160,10061161,50568680,257129888,1320619176, 6842177174,35722456976,187772944964,992991472328, 5279633960181,28208037066528,151373637844440, 815568695756496,4410124252008112] |