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 | 3 |
| 3 | 9 |
| 4 | 25 |
| 5 | 75 |
| 6 | 223 |
| 7 | 665 |
| 8 | 1993 |
| 9 | 5971 |
| 10 | 17903 |
| 11 | 53697 |
| 12 | 161065 |
| 13 | 483163 |
| 14 | 1449439 |
| 15 | 4348233 |
| 16 | 13044585 |
| 17 | 39133571 |
| 18 | 117400431 |
| 19 | 352200881 |
| 20 | 1056601993 |
| 21 | 3169805003 |
| 22 | 9509413535 |
| 23 | 28528238329 |
| 24 | 85584711561 |
| 25 | 256754129459 |
| 26 | 770262380399 |
| 27 | 2310787129121 |
| 28 | 6932361368937 |