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 | 5 |
| 4 | 17 |
| 5 | 75 |
| 6 | 407 |
| 7 | 2621 |
| 8 | 19524 |
| 9 | 165090 |
| 10 | 1561900 |
| 11 | 16345264 |
| 12 | 187452475 |
| 13 | 2337729329 |
| 14 | 31497068553 |
| 15 | 455930417721 |
| 16 | 7056447326642 |
| 17 | 116279714536838 |
| 18 | 2032547040624336 |
| 19 | 37563420959431569 |
| 20 | 731810131489893185 |
| 21 | 14989602024463575408 |
| 22 | 322032777284323744894 |
| 23 | 7240745954488939549295 |