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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 5 |
| 3 | 15 |
| 4 | 50 |
| 5 | 164 |
| 6 | 572 |
| 7 | 2007 |
| 8 | 7147 |
| 9 | 25744 |
| 10 | 94470 |
| 11 | 345562 |
| 12 | 1283521 |
| 13 | 4774425 |
| 14 | 17870925 |
| 15 | 67071406 |
| 16 | 253596740 |
| 17 | 957841394 |
| 18 | 3641689270 |
| 19 | 13852713872 |
| 20 | 52882413683 |
| 21 | 202064486221 |
| 22 | 775138650253 |
| 23 | 2972225528641 |
| 24 | 11437906305874 |
| 25 | 44025442187961 |
| 26 | 169850215967115 |
| 27 | 655535281281558 |
| 28 | 2536205112396006 |
[1,2,5,15,50,164,572,2007,7147,25744,94470,345562, 1283521,4774425,17870925,67071406,253596740, 957841394,3641689270,13852713872,52882413683, 202064486221,775138650253,2972225528641, 11437906305874,44025442187961,169850215967115, 655535281281558,2536205112396006] |