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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 10 |
| 4 | 40 |
| 5 | 129 |
| 6 | 537 |
| 7 | 1933 |
| 8 | 8328 |
| 9 | 31833 |
| 10 | 140729 |
| 11 | 559013 |
| 12 | 2518826 |
| 13 | 10280324 |
| 14 | 46991877 |
| 15 | 195714236 |
| 16 | 904660544 |
| 17 | 3827438751 |
| 18 | 17850086730 |
| 19 | 76473277330 |
| 20 | 359252690128 |
| 21 | 1554944844436 |
| 22 | 7349047127951 |
| 23 | 32080478571693 |
| 24 | 152395736480523 |
| 25 | 670039535488503 |
| 26 | 3196878057937120 |
| 27 | 14142253394919290 |
[1,1,4,10,40,129,537,1933,8328,31833,140729, 559013,2518826,10280324,46991877,195714236, 904660544,3827438751,17850086730,76473277330, 359252690128,1554944844436,7349047127951, 32080478571693,152395736480523,670039535488503, 3196878057937120,14142253394919290] |