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 | 1 |
| 1 | 5 |
| 2 | 20 |
| 3 | 75 |
| 4 | 279 |
| 5 | 1040 |
| 6 | 3881 |
| 7 | 14485 |
| 8 | 54060 |
| 9 | 201755 |
| 10 | 752959 |
| 11 | 2810080 |
| 12 | 10487361 |
| 13 | 39139365 |
| 14 | 146070100 |
| 15 | 545141035 |
| 16 | 2034494039 |
| 17 | 7592835120 |
| 18 | 28336846441 |
| 19 | 105754550645 |
| 20 | 394681356140 |
| 21 | 1472970873915 |
| 22 | 5497202139519 |
| 23 | 20515837684160 |
| 24 | 76566148597121 |
| 25 | 285748756704325 |