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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | -1 |
| 2 | -4 |
| 3 | -15 |
| 4 | -56 |
| 5 | -209 |
| 6 | -780 |
| 7 | -2911 |
| 8 | -10864 |
| 9 | -40545 |
| 10 | -151316 |
| 11 | -564719 |
| 12 | -2107560 |
| 13 | -7865521 |
| 14 | -29354524 |
| 15 | -109552575 |
| 16 | -408855776 |
| 17 | -1525870529 |
| 18 | -5694626340 |
| 19 | -21252634831 |
| 20 | -79315912984 |
| 21 | -296011017105 |
| 22 | -1104728155436 |
| 23 | -4122901604639 |
| 24 | -15386878263120 |
| 25 | -57424611447841 |
[0,-1,-4,-15,-56,-209,-780,-2911,-10864,-40545, -151316,-564719,-2107560,-7865521,-29354524, -109552575,-408855776,-1525870529,-5694626340, -21252634831,-79315912984,-296011017105, -1104728155436,-4122901604639,-15386878263120, -57424611447841] |