This is a front-end for the Online Encyclopedia of Integer Sequences, made by Christian Perfect. The idea is to provide OEIS entries in non-ancient HTML, and then to think about how they're presented visually. The source code is on GitHub.
| n | a(n) |
|---|---|
| 0 | 3 |
| 1 | 3 |
| 2 | 6 |
| 3 | 18 |
| 4 | 72 |
| 5 | 360 |
| 6 | 2160 |
| 7 | 15120 |
| 8 | 120960 |
| 9 | 1088640 |
| 10 | 10886400 |
| 11 | 119750400 |
| 12 | 1437004800 |
| 13 | 18681062400 |
| 14 | 261534873600 |
| 15 | 3923023104000 |
| 16 | 62768369664000 |
| 17 | 1067062284288000 |
| 18 | 19207121117184000 |
| 19 | 364935301226496000 |
| 20 | 7298706024529920000 |
| 21 | 153272826515128320000 |