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 | 0 |
| 2 | 0 |
| 3 | 1 |
| 4 | 4 |
| 5 | 17 |
| 6 | 68 |
| 7 | 292 |
| 8 | 1252 |
| 9 | 5670 |
| 10 | 26114 |
| 11 | 126073 |
| 12 | 621914 |
| 13 | 3206277 |
| 14 | 16888898 |
| 15 | 92771126 |
| 16 | 519907322 |
| 17 | 3032369590 |
| 18 | 18012896770 |
| 19 | 111155162265 |
| 20 | 697399200274 |
| 21 | 4537750415991 |
| 22 | 29972920817228 |
| 23 | 204993708306706 |
| 24 | 1421278374189924 |
| 25 | 10188372221843166 |
| 26 | 73948157842293620 |