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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 1 |
| 2 | 5 |
| 3 | 28 |
| 4 | 155 |
| 5 | 859 |
| 6 | 4760 |
| 7 | 26377 |
| 8 | 146165 |
| 9 | 809956 |
| 10 | 4488275 |
| 11 | 24871243 |
| 12 | 137821040 |
| 13 | 763718929 |
| 14 | 4232057765 |
| 15 | 23451445612 |
| 16 | 129953401355 |
| 17 | 720121343611 |
| 18 | 3990466922120 |
| 19 | 22112698641433 |
| 20 | 122534893973525 |
| 21 | 679012565791924 |
| 22 | 3762667510880195 |
| 23 | 20850375251776747 |
[0,1,5,28,155,859,4760,26377,146165,809956, 4488275,24871243,137821040,763718929,4232057765, 23451445612,129953401355,720121343611, 3990466922120,22112698641433,122534893973525, 679012565791924,3762667510880195, 20850375251776747] |