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 | 3 |
| 3 | 7 |
| 4 | 19 |
| 5 | 55 |
| 6 | 222 |
| 7 | 1303 |
| 8 | 13845 |
| 9 | 289796 |
| 10 | 12309107 |
| 11 | 1031600490 |
| 12 | 166135132131 |
| 13 | 50669199124597 |
| 14 | 29104991031790932 |
| 15 | 31455641633255556350 |
| 16 | 64032500451659605651790 |
| 17 | 245999928109779646497947269 |
| 18 | 1787823789106309664923287885113 |