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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 2 |
| 2 | 4 |
| 3 | 6 |
| 4 | 24 |
| 5 | 90 |
| 6 | 252 |
| 7 | 574 |
| 8 | 1136 |
| 9 | 2034 |
| 10 | 3380 |
| 11 | 5302 |
| 12 | 7944 |
| 13 | 11466 |
| 14 | 16044 |
| 15 | 21870 |
| 16 | 29152 |
| 17 | 38114 |
| 18 | 48996 |
| 19 | 62054 |
| 20 | 77560 |
| 21 | 95802 |
| 22 | 117084 |
| 23 | 141726 |
| 24 | 170064 |
| 25 | 202450 |
| 26 | 239252 |
| 27 | 280854 |
| 28 | 327656 |
| 29 | 380074 |
| 30 | 438540 |
| 31 | 503502 |
| 32 | 575424 |
| 33 | 654786 |
| 34 | 742084 |
| 35 | 837830 |
| 36 | 942552 |
| 37 | 1056794 |
| 38 | 1181116 |
[0,2,4,6,24,90,252,574,1136,2034,3380,5302,7944, 11466,16044,21870,29152,38114,48996,62054,77560, 95802,117084,141726,170064,202450,239252,280854, 327656,380074,438540,503502,575424,654786,742084, 837830,942552,1056794,1181116] |