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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 4 |
| 5 | 12 |
| 6 | 34 |
| 7 | 108 |
| 8 | 350 |
| 9 | 1170 |
| 10 | 3980 |
| 11 | 13776 |
| 12 | 48286 |
| 13 | 171124 |
| 14 | 611994 |
| 15 | 2206018 |
| 16 | 8006120 |
| 17 | 29229932 |
| 18 | 107280390 |
| 19 | 395593940 |
| 20 | 1464883654 |
| 21 | 5445038132 |
| 22 | 20308989646 |
| 23 | 75985676050 |
| 24 | 285111556728 |
| 25 | 1072594810368 |
| 26 | 4044869862236 |
| 27 | 15287690645590 |
| 28 | 57899780087350 |
| 29 | 219708252658174 |
| 30 | 835205725190634 |
| 31 | 3180292173415490 |
[1,1,2,4,12,34,108,350,1170,3980,13776,48286, 171124,611994,2206018,8006120,29229932,107280390, 395593940,1464883654,5445038132,20308989646, 75985676050,285111556728,1072594810368, 4044869862236,15287690645590,57899780087350, 219708252658174,835205725190634,3180292173415490] |