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 | 0 |
| 2 | 1 |
| 3 | 5 |
| 4 | 17 |
| 5 | 51 |
| 6 | 147 |
| 7 | 419 |
| 8 | 1191 |
| 9 | 3383 |
| 10 | 9607 |
| 11 | 27279 |
| 12 | 77455 |
| 13 | 219919 |
| 14 | 624415 |
| 15 | 1772895 |
| 16 | 5033759 |
| 17 | 14292287 |
| 18 | 40579903 |
| 19 | 115217983 |
| 20 | 327136895 |
| 21 | 928835455 |
| 22 | 2637230207 |
| 23 | 7487852799 |
| 24 | 21260161279 |
| 25 | 60363694335 |
| 26 | 171389837823 |
| 27 | 486624896511 |
| 28 | 1381667623423 |
| 29 | 3922950583295 |