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 | 0 |
| 2 | 1 |
| 3 | 1 |
| 4 | 7 |
| 5 | 11 |
| 6 | 51 |
| 7 | 105 |
| 8 | 399 |
| 9 | 967 |
| 10 | 3299 |
| 11 | 8789 |
| 12 | 28271 |
| 13 | 79443 |
| 14 | 247507 |
| 15 | 716353 |
| 16 | 2193583 |
| 17 | 6452639 |
| 18 | 19575075 |
| 19 | 58095597 |
| 20 | 175350735 |
| 21 | 522947755 |
| 22 | 1574075603 |
| 23 | 4706879321 |
| 24 | 14146450127 |
| 25 | 42363311991 |
| 26 | 127217598691 |
| 27 | 381275400325 |
| 28 | 1144458922159 |