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| n | a(n) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 3 |
| 4 | 4 |
| 5 | 15 |
| 6 | 23 |
| 7 | 94 |
| 8 | 155 |
| 9 | 661 |
| 10 | 1139 |
| 11 | 4983 |
| 12 | 8844 |
| 13 | 39362 |
| 14 | 71360 |
| 15 | 321561 |
| 16 | 592361 |
| 17 | 2694421 |
| 18 | 5025849 |
| 19 | 23029195 |
| 20 | 43388208 |
| 21 | 199990961 |
| 22 | 379900479 |
| 23 | 1759636142 |
| 24 | 3365582261 |
| 25 | 15652514944 |
| 26 | 30112397278 |
| 27 | 140531706444 |
| 28 | 271707661708 |
[1,1,3,4,15,23,94,155,661,1139,4983,8844,39362, 71360,321561,592361,2694421,5025849,23029195, 43388208,199990961,379900479,1759636142, 3365582261,15652514944,30112397278,140531706444, 271707661708] |