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 | 4 |
| 2 | 16 |
| 3 | 62 |
| 4 | 233 |
| 5 | 855 |
| 6 | 3083 |
| 7 | 10978 |
| 8 | 38746 |
| 9 | 135924 |
| 10 | 474955 |
| 11 | 1655789 |
| 12 | 5766389 |
| 13 | 20080608 |
| 14 | 69976772 |
| 15 | 244166410 |
| 16 | 853410637 |
| 17 | 2988825507 |
| 18 | 10490538559 |
| 19 | 36905911166 |
| 20 | 130139760590 |
| 21 | 459970519296 |
| 22 | 1629395348591 |
| 23 | 5784362027257 |