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 | 1 |
| 2 | 5 |
| 3 | 52 |
| 4 | 437 |
| 5 | 3342 |
| 6 | 21734 |
| 7 | 155685 |
| 8 | 1153475 |
| 9 | 8422634 |
| 10 | 60853524 |
| 11 | 438333924 |
| 12 | 3175356262 |
| 13 | 23029289042 |
| 14 | 166811590187 |
| 15 | 1207552045117 |
| 16 | 8742472744191 |
| 17 | 63314217459429 |
| 18 | 458530998840648 |
| 19 | 3320452657540486 |
| 20 | 24044504957977794 |
| 21 | 174117682083426003 |
| 22 | 1260888371373690768 |