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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 2 |
| 3 | 6 |
| 4 | 18 |
| 5 | 58 |
| 6 | 174 |
| 7 | 536 |
| 8 | 1656 |
| 9 | 4947 |
| 10 | 14800 |
| 11 | 43157 |
| 12 | 126572 |
| 13 | 364070 |
| 14 | 1039926 |
| 15 | 2938898 |
| 16 | 8223400 |
| 17 | 22846370 |
| 18 | 62930113 |
| 19 | 172177400 |
| 20 | 467002792 |
| 21 | 1259736804 |
| 22 | 3371190792 |
| 23 | 8973530491 |
| 24 | 23728305128 |
| 25 | 62421018163 |
| 26 | 163255839779 |
| 27 | 424842462529 |
| 28 | 1100006243934 |
| 29 | 2834558927244 |
| 30 | 7270915592897 |
[1,1,2,6,18,58,174,536,1656,4947,14800,43157, 126572,364070,1039926,2938898,8223400,22846370, 62930113,172177400,467002792,1259736804, 3371190792,8973530491,23728305128,62421018163, 163255839779,424842462529,1100006243934, 2834558927244,7270915592897] |