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 | 0 |
| 2 | 1 |
| 3 | 1 |
| 4 | 4 |
| 5 | 9 |
| 6 | 27 |
| 7 | 76 |
| 8 | 226 |
| 9 | 680 |
| 10 | 2078 |
| 11 | 6441 |
| 12 | 20153 |
| 13 | 63684 |
| 14 | 202732 |
| 15 | 649930 |
| 16 | 2095854 |
| 17 | 6794684 |
| 18 | 22131765 |
| 19 | 72393439 |
| 20 | 237703654 |
| 21 | 783198068 |
| 22 | 2588645047 |
| 23 | 8580674778 |
| 24 | 28517805357 |
| 25 | 95009277576 |
| 26 | 317242351135 |
| 27 | 1061500510809 |
| 28 | 3558683892258 |
| 29 | 11952025977378 |
| 30 | 40209157279701 |