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 | 2 |
| 2 | 6 |
| 3 | 20 |
| 4 | 74 |
| 5 | 292 |
| 6 | 1218 |
| 7 | 5308 |
| 8 | 24034 |
| 9 | 112484 |
| 10 | 542346 |
| 11 | 2686268 |
| 12 | 13639226 |
| 13 | 70863652 |
| 14 | 376208706 |
| 15 | 2038335580 |
| 16 | 11259474754 |
| 17 | 63353211332 |
| 18 | 362819139978 |
| 19 | 2113410084188 |
| 20 | 12513610048154 |
| 21 | 75274067489284 |
| 22 | 459782361574146 |
| 23 | 2850369932150908 |
| 24 | 17926893505949986 |
| 25 | 114337654086861092 |