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) |
|---|---|
| 3 | 1 |
| 4 | 3 |
| 5 | 9 |
| 6 | 31 |
| 7 | 101 |
| 8 | 319 |
| 9 | 985 |
| 10 | 2991 |
| 11 | 8973 |
| 12 | 26687 |
| 13 | 78877 |
| 14 | 232083 |
| 15 | 680645 |
| 16 | 1991487 |
| 17 | 5817073 |
| 18 | 16971415 |
| 19 | 49474389 |
| 20 | 144149959 |
| 21 | 419869065 |
| 22 | 1222785111 |
| 23 | 3561052305 |
| 24 | 10371483259 |
| 25 | 30211361481 |
| 26 | 88022087975 |
| 27 | 256521698097 |
| 28 | 747794233779 |