| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 0 |
| 2 | 0 |
| 3 | 6 |
| 4 | 33 |
| 5 | 144 |
| 6 | 570 |
| 7 | 2118 |
| 8 | 7587 |
| 9 | 26448 |
| 10 | 90420 |
| 11 | 304470 |
| 12 | 1013061 |
| 13 | 3338112 |
| 14 | 10911150 |
| 15 | 35423862 |
| 16 | 114342855 |
| 17 | 367242336 |
| 18 | 1174368360 |
| 19 | 3741029094 |
| 20 | 11876859369 |
| 21 | 37591894320 |
| 22 | 118659631650 |
| 23 | 373630740966 |
| 24 | 1173847761003 |
[0,0,0,6,33,144,570,2118,7587,26448,90420,304470, 1013061,3338112,10911150,35423862,114342855, 367242336,1174368360,3741029094,11876859369, 37591894320,118659631650,373630740966, 1173847761003] |