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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 7 |
| 3 | 7 |
| 4 | 56 |
| 5 | 105 |
| 6 | 497 |
| 7 | 1232 |
| 8 | 4711 |
| 9 | 13335 |
| 10 | 46312 |
| 11 | 139657 |
| 12 | 463841 |
| 13 | 1441440 |
| 14 | 4688327 |
| 15 | 14778407 |
| 16 | 47596696 |
| 17 | 151045545 |
| 18 | 484222417 |
| 19 | 1541541232 |
| 20 | 4931098151 |
| 21 | 15721886775 |
| 22 | 50239573832 |
| 23 | 160292781257 |
| 24 | 511969798081 |
| 25 | 1634019266880 |
| 26 | 5217807853447 |
| 27 | 16655942721607 |
| 28 | 53180597695736 |
| 29 | 169772196746985 |
[1,0,7,7,56,105,497,1232,4711,13335,46312,139657, 463841,1441440,4688327,14778407,47596696, 151045545,484222417,1541541232,4931098151, 15721886775,50239573832,160292781257,511969798081, 1634019266880,5217807853447,16655942721607, 53180597695736,169772196746985] |