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| n | a(n) |
|---|---|
| 0 | 0 |
| 1 | 3 |
| 2 | 15 |
| 3 | 42 |
| 4 | 90 |
| 5 | 165 |
| 6 | 273 |
| 7 | 420 |
| 8 | 612 |
| 9 | 855 |
| 10 | 1155 |
| 11 | 1518 |
| 12 | 1950 |
| 13 | 2457 |
| 14 | 3045 |
| 15 | 3720 |
| 16 | 4488 |
| 17 | 5355 |
| 18 | 6327 |
| 19 | 7410 |
| 20 | 8610 |
| 21 | 9933 |
| 22 | 11385 |
| 23 | 12972 |
| 24 | 14700 |
| 25 | 16575 |
| 26 | 18603 |
| 27 | 20790 |
| 28 | 23142 |
| 29 | 25665 |
| 30 | 28365 |
| 31 | 31248 |
| 32 | 34320 |
| 33 | 37587 |
| 34 | 41055 |
| 35 | 44730 |
| 36 | 48618 |
| 37 | 52725 |
| 38 | 57057 |
| 39 | 61620 |
[0,3,15,42,90,165,273,420,612,855,1155,1518,1950, 2457,3045,3720,4488,5355,6327,7410,8610,9933, 11385,12972,14700,16575,18603,20790,23142,25665, 28365,31248,34320,37587,41055,44730,48618,52725, 57057,61620] |