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 | 5 |
| 3 | 18 |
| 4 | 75 |
| 5 | 396 |
| 6 | 2052 |
| 7 | 11586 |
| 8 | 71787 |
| 9 | 458352 |
| 10 | 3103668 |
| 11 | 22202874 |
| 12 | 164999826 |
| 13 | 1281692088 |
| 14 | 10371684312 |
| 15 | 86973240204 |
| 16 | 755908929603 |
| 17 | 6794220017664 |
| 18 | 63008287321788 |
| 19 | 602270212069098 |
| 20 | 5924679849081126 |
| 21 | 59897824980579576 |
| 22 | 621672797654084520 |
| 23 | 6616610400436719588 |