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) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 3 |
| 4 | 3 |
| 5 | 9 |
| 6 | 45 |
| 7 | 315 |
| 8 | 315 |
| 9 | 945 |
| 10 | 4725 |
| 11 | 33075 |
| 12 | 297675 |
| 13 | 3274425 |
| 14 | 42567525 |
| 15 | 638512875 |
| 16 | 638512875 |
| 17 | 1915538625 |
| 18 | 9577693125 |
| 19 | 67043851875 |
| 20 | 603394666875 |
| 21 | 6637341335625 |
| 22 | 86285437363125 |
| 23 | 1294281560446875 |
| 24 | 22002786527596875 |
| 25 | 418052944024340625 |
| 26 | 8779111824511153125 |
| 27 | 201919571963756521875 |