| n | a(n) |
|---|---|
| 1 | 0 |
| 2 | 5 |
| 3 | 2 |
| 4 | 20 |
| 5 | 27 |
| 6 | 108 |
| 7 | 191 |
| 8 | 599 |
| 9 | 1261 |
| 10 | 3503 |
| 11 | 8019 |
| 12 | 20956 |
| 13 | 49932 |
| 14 | 126833 |
| 15 | 308197 |
| 16 | 772321 |
| 17 | 1894368 |
| 18 | 4716189 |
| 19 | 11620491 |
| 20 | 28839210 |
| 21 | 71214717 |
| 22 | 176468284 |
| 23 | 436228102 |
| 24 | 1080165740 |
| 25 | 2671530008 |
| 26 | 6612751510 |
| 27 | 16359100711 |
| 28 | 40486188269 |
| 29 | 100169626090 |
[0,5,2,20,27,108,191,599,1261,3503,8019,20956, 49932,126833,308197,772321,1894368,4716189, 11620491,28839210,71214717,176468284,436228102, 1080165740,2671530008,6612751510,16359100711, 40486188269,100169626090] |