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) |
|---|---|
| 1 | 1 |
| 2 | 6 |
| 3 | 19 |
| 4 | 72 |
| 5 | 289 |
| 6 | 996 |
| 7 | 3325 |
| 8 | 11415 |
| 9 | 39720 |
| 10 | 138689 |
| 11 | 483837 |
| 12 | 1682961 |
| 13 | 5845649 |
| 14 | 20310166 |
| 15 | 70604782 |
| 16 | 245504404 |
| 17 | 853649448 |
| 18 | 2967979455 |
| 19 | 10318546476 |
| 20 | 35873587105 |
| 21 | 124720541039 |
| 22 | 433616480871 |
| 23 | 1507558685202 |
| 24 | 5241330944265 |