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 | 0 |
| 1 | 1 |
| 2 | 4 |
| 3 | 19 |
| 4 | 74 |
| 5 | 305 |
| 6 | 1208 |
| 7 | 4863 |
| 8 | 19398 |
| 9 | 77709 |
| 10 | 310612 |
| 11 | 1242907 |
| 12 | 4970722 |
| 13 | 19884713 |
| 14 | 79535216 |
| 15 | 318148151 |
| 16 | 1272578046 |
| 17 | 5090341317 |
| 18 | 20361307020 |
| 19 | 81445344595 |
| 20 | 325781145370 |
| 21 | 1303125047521 |
| 22 | 5212499258024 |
| 23 | 20849998896239 |
| 24 | 83399991856694 |