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 | 7 |
| 2 | 19 |
| 3 | 53 |
| 4 | 149 |
| 5 | 421 |
| 6 | 1193 |
| 7 | 3387 |
| 8 | 9627 |
| 9 | 27383 |
| 10 | 77923 |
| 11 | 221805 |
| 12 | 631469 |
| 13 | 1797957 |
| 14 | 5119593 |
| 15 | 14578387 |
| 16 | 41514003 |
| 17 | 118218823 |
| 18 | 336653331 |
| 19 | 958698053 |
| 20 | 2730124261 |
| 21 | 7774706437 |
| 22 | 22140438345 |
| 23 | 63050541515 |
| 24 | 179552587883 |
| 25 | 511322221559 |