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) |
|---|---|
| 1 | 1 |
| 2 | 3 |
| 3 | 9 |
| 4 | 21 |
| 5 | 63 |
| 6 | 147 |
| 7 | 357 |
| 8 | 903 |
| 9 | 2499 |
| 10 | 6069 |
| 11 | 13915 |
| 12 | 29095 |
| 13 | 59455 |
| 14 | 142945 |
| 15 | 320045 |
| 16 | 643885 |
| 17 | 1367465 |
| 18 | 3287735 |
| 19 | 6779135 |
| 20 | 13853015 |
| 21 | 30262595 |
| 22 | 61773745 |