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 | 5 |
| 2 | 21 |
| 3 | 93 |
| 4 | 409 |
| 5 | 1853 |
| 6 | 8333 |
| 7 | 37965 |
| 8 | 172265 |
| 9 | 787557 |
| 10 | 3593465 |
| 11 | 16477845 |
| 12 | 75481105 |
| 13 | 346960613 |
| 14 | 1593924045 |
| 15 | 7341070889 |
| 16 | 33798930541 |
| 17 | 155915787353 |
| 18 | 719101961769 |
| 19 | 3321659652529 |
| 20 | 15341586477457 |
| 21 | 70944927549085 |
| 22 | 328054694768261 |
| 23 | 1518490945278377 |
| 24 | 7028570356547189 |
| 25 | 32560476643826933 |
| 26 | 150838831585499069 |