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 | 0 |
| 1 | 1 |
| 2 | 1 |
| 3 | 15 |
| 4 | 45 |
| 5 | 231 |
| 6 | 861 |
| 7 | 3655 |
| 8 | 14365 |
| 9 | 58311 |
| 10 | 232221 |
| 11 | 932295 |
| 12 | 3725085 |
| 13 | 14913991 |
| 14 | 59639581 |
| 15 | 238612935 |
| 16 | 954386205 |
| 17 | 3817763271 |
| 18 | 15270790941 |
| 19 | 61084037575 |
| 20 | 244335101725 |
| 21 | 977343902151 |
| 22 | 3909371414301 |
| 23 | 15637499638215 |
| 24 | 62549981775645 |