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 | 1 |
| 2 | 1 |
| 3 | 1 |
| 4 | 3 |
| 5 | 7 |
| 6 | 15 |
| 7 | 33 |
| 8 | 81 |
| 9 | 225 |
| 10 | 679 |
| 11 | 2139 |
| 12 | 6931 |
| 13 | 23185 |
| 14 | 80809 |
| 15 | 295141 |
| 16 | 1128487 |
| 17 | 4492363 |
| 18 | 18506923 |
| 19 | 78584193 |
| 20 | 343414489 |
| 21 | 1544535129 |
| 22 | 7151822771 |
| 23 | 34086446307 |
| 24 | 167058478355 |
| 25 | 840700482197 |
| 26 | 4337529697349 |
| 27 | 22915761303125 |
| 28 | 123863743341203 |
| 29 | 684588061704611 |
| 30 | 3867278506969535 |