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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | -6 |
| 2 | -6 |
| 3 | -20 |
| 4 | -90 |
| 5 | -468 |
| 6 | -2652 |
| 7 | -15912 |
| 8 | -99450 |
| 9 | -640900 |
| 10 | -4229940 |
| 11 | -28455960 |
| 12 | -194449060 |
| 13 | -1346185800 |
| 14 | -9423300600 |
| 15 | -66591324240 |
| 16 | -474463185210 |
| 17 | -3404971093860 |
| 18 | -24591457900100 |
| 19 | -178611641590200 |
| 20 | -1303864983608460 |
| 21 | -9561676546462040 |
| 22 | -70408709114856840 |
[1,-6,-6,-20,-90,-468,-2652,-15912,-99450,-640900, -4229940,-28455960,-194449060,-1346185800, -9423300600,-66591324240,-474463185210, -3404971093860,-24591457900100,-178611641590200, -1303864983608460,-9561676546462040, -70408709114856840] |