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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 10 |
| 4 | 45 |
| 5 | 137 |
| 6 | 651 |
| 7 | 2225 |
| 8 | 10782 |
| 9 | 39551 |
| 10 | 193668 |
| 11 | 744173 |
| 12 | 3667892 |
| 13 | 14564363 |
| 14 | 72089043 |
| 15 | 293344604 |
| 16 | 1456043669 |
| 17 | 6038218547 |
| 18 | 30028994375 |
| 19 | 126420217768 |
| 20 | 629561111620 |
| 21 | 2683075985049 |
| 22 | 13374552608998 |
| 23 | 57581209527148 |
| 24 | 287235901179914 |
| 25 | 1247233541894547 |
| 26 | 6224972949360422 |
| 27 | 27227496594651898 |
[1,1,4,10,45,137,651,2225,10782,39551,193668, 744173,3667892,14564363,72089043,293344604, 1456043669,6038218547,30028994375,126420217768, 629561111620,2683075985049,13374552608998, 57581209527148,287235901179914,1247233541894547, 6224972949360422,27227496594651898] |