The OEIS is supported by the many generous donors to the OEIS Foundation.
| n | a(n) |
|---|---|
| 1 | 3 |
| 2 | 18 |
| 3 | 150 |
| 4 | 588 |
| 5 | 3630 |
| 6 | 7098 |
| 7 | 20808 |
| 8 | 32490 |
| 9 | 69828 |
| 10 | 176610 |
| 11 | 230640 |
| 12 | 468198 |
| 13 | 706020 |
| 14 | 854238 |
| 15 | 1219368 |
| 16 | 1971918 |
| 17 | 3028470 |
| 18 | 3460530 |
| 19 | 5036658 |
| 20 | 6351660 |
| 21 | 7098228 |
| 22 | 9735960 |
| 23 | 11862858 |
| 24 | 15683580 |
| 25 | 22129968 |
| 26 | 26012550 |
| 27 | 28135068 |
| 28 | 32767038 |
| 29 | 35286570 |
[3,18,150,588,3630,7098,20808,32490,69828,176610, 230640,468198,706020,854238,1219368,1971918, 3028470,3460530,5036658,6351660,7098228,9735960, 11862858,15683580,22129968,26012550,28135068, 32767038,35286570] |