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| n | a(n) |
|---|---|
| 1 | 18 |
| 2 | 254 |
| 3 | 1571 |
| 4 | 6335 |
| 5 | 19615 |
| 6 | 50743 |
| 7 | 115234 |
| 8 | 237066 |
| 9 | 451320 |
| 10 | 807180 |
| 11 | 1371293 |
| 12 | 2231489 |
| 13 | 3500861 |
| 14 | 5322205 |
| 15 | 7872820 |
| 16 | 11369668 |
| 17 | 16074894 |
| 18 | 22301706 |
| 19 | 30420615 |
| 20 | 40866035 |
| 21 | 54143243 |
| 22 | 70835699 |
| 23 | 91612726 |
[18,254,1571,6335,19615,50743,115234,237066, 451320,807180,1371293,2231489,3500861,5322205, 7872820,11369668,16074894,22301706,30420615, 40866035,54143243,70835699,91612726] |