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Reminder: The OEIS is hiring a new managing editor, and the application deadline is January 26.
| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 0 |
| 2 | 0 |
| 3 | 1 |
| 4 | 3 |
| 5 | 15 |
| 6 | 80 |
| 7 | 506 |
| 8 | 3710 |
| 9 | 30920 |
| 10 | 288591 |
| 11 | 2982109 |
| 12 | 33797241 |
| 13 | 416832633 |
| 14 | 5557768440 |
| 15 | 79661347641 |
| 16 | 1221473997164 |
| 17 | 19950741953682 |
| 18 | 345812860530488 |
| 19 | 6339902443058941 |
| 20 | 122571447232472866 |
| 21 | 2492286093726948268 |
[1,0,0,1,3,15,80,506,3710,30920,288591,2982109, 33797241,416832633,5557768440,79661347641, 1221473997164,19950741953682,345812860530488, 6339902443058941,122571447232472866, 2492286093726948268] |