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| n | a(n) |
|---|---|
| 0 | 1 |
| 1 | 5 |
| 2 | 5 |
| 3 | 30 |
| 4 | 80 |
| 5 | 405 |
| 6 | 1505 |
| 7 | 7255 |
| 8 | 31155 |
| 9 | 149455 |
| 10 | 688655 |
| 11 | 3334880 |
| 12 | 15965130 |
| 13 | 78294155 |
| 14 | 383599455 |
| 15 | 1903940030 |
| 16 | 9474093880 |
| 17 | 47514889255 |
| 18 | 239112929655 |
| 19 | 1209724381330 |
| 20 | 6140755848280 |
| 21 | 31294613247255 |
| 22 | 159963286607755 |
| 23 | 820204107625155 |
| 24 | 4216569874416955 |
| 25 | 21732350726100905 |
[1,5,5,30,80,405,1505,7255,31155,149455,688655, 3334880,15965130,78294155,383599455,1903940030, 9474093880,47514889255,239112929655,1209724381330, 6140755848280,31294613247255,159963286607755, 820204107625155,4216569874416955, 21732350726100905] |