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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 2 |
| 2 | 15 |
| 3 | 52 |
| 4 | 213 |
| 5 | 834 |
| 6 | 3043 |
| 7 | 11576 |
| 8 | 41601 |
| 9 | 152458 |
| 10 | 544039 |
| 11 | 1950132 |
| 12 | 6895773 |
| 13 | 24403302 |
| 14 | 85542339 |
| 15 | 300101048 |
| 16 | 1044436937 |
| 17 | 3639851814 |
| 18 | 12594713911 |
| 19 | 43660404108 |
| 20 | 150357976533 |
| 21 | 518991977194 |
| 22 | 1780132570723 |
| 23 | 6122965091976 |
| 24 | 20928650616113 |
| 25 | 71779065646510 |
| 26 | 244590689773839 |
[1,2,15,52,213,834,3043,11576,41601,152458,544039, 1950132,6895773,24403302,85542339,300101048, 1044436937,3639851814,12594713911,43660404108, 150357976533,518991977194,1780132570723, 6122965091976,20928650616113,71779065646510, 244590689773839] |