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 | 3 |
| 2 | 9 |
| 3 | 21 |
| 4 | 51 |
| 5 | 123 |
| 6 | 285 |
| 7 | 669 |
| 8 | 1569 |
| 9 | 3603 |
| 10 | 8343 |
| 11 | 19335 |
| 12 | 44193 |
| 13 | 101577 |
| 14 | 233697 |
| 15 | 532569 |
| 16 | 1218345 |
| 17 | 2789475 |
| 18 | 6343161 |
| 19 | 14464101 |
| 20 | 33004269 |
| 21 | 74923059 |
| 22 | 170440203 |
| 23 | 387945747 |
| 24 | 879473277 |
| 25 | 1997066751 |
| 26 | 4536975315 |
| 27 | 10273846185 |