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 | 2 |
| 3 | 9 |
| 4 | 42 |
| 5 | 235 |
| 6 | 1605 |
| 7 | 12446 |
| 8 | 108836 |
| 9 | 1061565 |
| 10 | 11402565 |
| 11 | 133806134 |
| 12 | 1703059974 |
| 13 | 23366177055 |
| 14 | 343788954691 |
| 15 | 5399655967642 |
| 16 | 90173526680152 |
| 17 | 1595513146457993 |
| 18 | 29817130502252169 |
| 19 | 586883850601630054 |
| 20 | 12135450890055396810 |
| 21 | 263012688923611212107 |
| 22 | 5962155058714267567319 |