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) |
|---|---|
| 4 | 1 |
| 5 | 3 |
| 6 | 9 |
| 7 | 31 |
| 8 | 105 |
| 9 | 352 |
| 10 | 1168 |
| 11 | 3828 |
| 12 | 12396 |
| 13 | 39698 |
| 14 | 125878 |
| 15 | 395686 |
| 16 | 1234426 |
| 17 | 3825911 |
| 18 | 11790893 |
| 19 | 36160491 |
| 20 | 110429221 |
| 21 | 336001043 |
| 22 | 1019092233 |
| 23 | 3082348295 |
| 24 | 9300339633 |
| 25 | 28002492673 |
| 26 | 84156758459 |
| 27 | 252507279805 |
| 28 | 756547966323 |