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 | 3 |
| 2 | 9 |
| 3 | 30 |
| 4 | 99 |
| 5 | 324 |
| 6 | 1062 |
| 7 | 3483 |
| 8 | 11421 |
| 9 | 37449 |
| 10 | 122796 |
| 11 | 402651 |
| 12 | 1320300 |
| 13 | 4329288 |
| 14 | 14195817 |
| 15 | 46548351 |
| 16 | 152632917 |
| 17 | 500486202 |
| 18 | 1641103659 |
| 19 | 5381209728 |
| 20 | 17645087790 |
| 21 | 57858574347 |
| 22 | 189719352225 |
| 23 | 622093320045 |
| 24 | 2039855683176 |