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 | 23 |
| 3 | 181 |
| 4 | 1425 |
| 5 | 11219 |
| 6 | 88327 |
| 7 | 695397 |
| 8 | 5474849 |
| 9 | 43103395 |
| 10 | 339352311 |
| 11 | 2671715093 |
| 12 | 21034368433 |
| 13 | 165603232371 |
| 14 | 1303791490535 |
| 15 | 10264728691909 |
| 16 | 80814038044737 |
| 17 | 636247575665987 |
| 18 | 5009166567283159 |
| 19 | 39437084962599285 |
| 20 | 310487513133511121 |
| 21 | 2444463020105489683 |