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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 16 |
| 2 | 74 |
| 3 | 274 |
| 4 | 1182 |
| 5 | 5146 |
| 6 | 22988 |
| 7 | 104008 |
| 8 | 475702 |
| 9 | 2193322 |
| 10 | 10178844 |
| 11 | 47489128 |
| 12 | 222537384 |
| 13 | 1046705104 |
| 14 | 4938809502 |
| 15 | 23367231454 |
| 16 | 110821701894 |
| 17 | 526680449962 |
| 18 | 2507653172738 |
| 19 | 11959006821214 |
| 20 | 57115337351332 |
| 21 | 273132653565388 |
[1,16,74,274,1182,5146,22988,104008,475702, 2193322,10178844,47489128,222537384,1046705104, 4938809502,23367231454,110821701894,526680449962, 2507653172738,11959006821214,57115337351332, 273132653565388] |