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 | 19 |
| 4 | 49 |
| 5 | 123 |
| 6 | 297 |
| 7 | 707 |
| 8 | 1697 |
| 9 | 4043 |
| 10 | 9561 |
| 11 | 22547 |
| 12 | 53073 |
| 13 | 124571 |
| 14 | 291721 |
| 15 | 682083 |
| 16 | 1592577 |
| 17 | 3713643 |
| 18 | 8650425 |
| 19 | 20132275 |
| 20 | 46818225 |
| 21 | 108804923 |
| 22 | 252718825 |
| 23 | 586701827 |
| 24 | 1361496929 |
| 25 | 3158352139 |
| 26 | 7324384281 |
| 27 | 16981143379 |
| 28 | 39360789521 |