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 | 6 |
| 3 | 39 |
| 4 | 284 |
| 5 | 2223 |
| 6 | 18267 |
| 7 | 155445 |
| 8 | 1358073 |
| 9 | 12111306 |
| 10 | 109802183 |
| 11 | 1009001571 |
| 12 | 9376972698 |
| 13 | 87978198364 |
| 14 | 832223905371 |
| 15 | 7928413841673 |
| 16 | 76002832317437 |
| 17 | 732578811761670 |
| 18 | 7095717550127526 |
| 19 | 69029297500888522 |
| 20 | 674181392461483212 |
| 21 | 6607910786529613248 |