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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 4 |
| 3 | 16 |
| 4 | 71 |
| 5 | 322 |
| 6 | 1455 |
| 7 | 6558 |
| 8 | 29548 |
| 9 | 133146 |
| 10 | 599998 |
| 11 | 2703794 |
| 12 | 12184181 |
| 13 | 54905857 |
| 14 | 247423522 |
| 15 | 1114970351 |
| 16 | 5024416818 |
| 17 | 22641646338 |
| 18 | 102030577247 |
| 19 | 459782762029 |
| 20 | 2071929748572 |
| 21 | 9336785189996 |
| 22 | 42074572144477 |
| 23 | 189601622519548 |
| 24 | 854406199035948 |
| 25 | 3850230516227419 |
[1,4,16,71,322,1455,6558,29548,133146,599998, 2703794,12184181,54905857,247423522,1114970351, 5024416818,22641646338,102030577247,459782762029, 2071929748572,9336785189996,42074572144477, 189601622519548,854406199035948,3850230516227419] |