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 | 3 |
| 3 | 9 |
| 4 | 33 |
| 5 | 99 |
| 6 | 525 |
| 7 | 3003 |
| 8 | 5445 |
| 9 | 5775 |
| 10 | 50505 |
| 11 | 53235 |
| 12 | 171171 |
| 13 | 525525 |
| 14 | 5073705 |
| 15 | 18999981 |
| 16 | 50555505 |
| 17 | 51666615 |
| 18 | 512272215 |
| 19 | 513828315 |
| 20 | 5026226205 |
| 21 | 5053553505 |
| 22 | 5184994815 |
| 23 | 5708778075 |
| 24 | 52252425225 |
| 25 | 502299992205 |
| 26 | 502875578205 |
| 27 | 524241142425 |
| 28 | 579024420975 |