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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 1 |
| 2 | 4 |
| 3 | 13 |
| 4 | 47 |
| 5 | 178 |
| 6 | 717 |
| 7 | 2931 |
| 8 | 12206 |
| 9 | 51725 |
| 10 | 222382 |
| 11 | 965695 |
| 12 | 4229004 |
| 13 | 18663791 |
| 14 | 82908381 |
| 15 | 370362024 |
| 16 | 1662456328 |
| 17 | 7494619832 |
| 18 | 33916523818 |
| 19 | 154011480462 |
| 20 | 701493894387 |
| 21 | 3204032461602 |
| 22 | 14671001493623 |
| 23 | 67330937214095 |
| 24 | 309654418218959 |
| 25 | 1426834603648238 |
| 26 | 6586249762098228 |
| 27 | 30451755568889279 |
[1,1,4,13,47,178,717,2931,12206,51725,222382, 965695,4229004,18663791,82908381,370362024, 1662456328,7494619832,33916523818,154011480462, 701493894387,3204032461602,14671001493623, 67330937214095,309654418218959,1426834603648238, 6586249762098228,30451755568889279] |