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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 2 |
| 5 | 6 |
| 6 | 13 |
| 7 | 32 |
| 8 | 87 |
| 9 | 243 |
| 10 | 654 |
| 11 | 1782 |
| 12 | 4914 |
| 13 | 13664 |
| 14 | 37994 |
| 15 | 106288 |
| 16 | 298890 |
| 17 | 844182 |
| 18 | 2391363 |
| 19 | 6796160 |
| 20 | 19369708 |
| 21 | 55345784 |
| 22 | 158489298 |
| 23 | 454795398 |
| 24 | 1307541690 |
| 25 | 3765741324 |
| 26 | 10862688116 |
| 27 | 31381059609 |
| 28 | 90780903460 |
| 29 | 262951692390 |
[1,1,1,2,6,13,32,87,243,654,1782,4914,13664,37994, 106288,298890,844182,2391363,6796160,19369708, 55345784,158489298,454795398,1307541690, 3765741324,10862688116,31381059609,90780903460, 262951692390] |