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 | 3 |
| 2 | 12 |
| 3 | 55 |
| 4 | 225 |
| 5 | 927 |
| 6 | 3729 |
| 7 | 14787 |
| 8 | 57888 |
| 9 | 224220 |
| 10 | 860022 |
| 11 | 3270744 |
| 12 | 12343899 |
| 13 | 46264257 |
| 14 | 172305837 |
| 15 | 638039136 |
| 16 | 2350109736 |
| 17 | 8613851832 |
| 18 | 31428857611 |
| 19 | 114187160631 |
| 20 | 413222547846 |
| 21 | 1489829356657 |
| 22 | 5352683946903 |
| 23 | 19167988920930 |
| 24 | 68427472477338 |
| 25 | 243559693397025 |