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 | 0 |
| 2 | 1 |
| 3 | 2 |
| 4 | 9 |
| 5 | 44 |
| 6 | 265 |
| 7 | 1854 |
| 8 | 10860 |
| 9 | 55314 |
| 10 | 259285 |
| 11 | 1178912 |
| 12 | 5382017 |
| 13 | 25157980 |
| 14 | 121727936 |
| 15 | 598440744 |
| 16 | 2954197380 |
| 17 | 14540741660 |
| 18 | 71135825805 |
| 19 | 345881286126 |
| 20 | 1675123912129 |
| 21 | 8108391695252 |
| 22 | 39291412775944 |
| 23 | 190687692089500 |
| 24 | 926601640342609 |
| 25 | 4505656310652572 |