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 | 4 |
| 4 | 16 |
| 5 | 68 |
| 6 | 301 |
| 7 | 1366 |
| 8 | 6301 |
| 9 | 29400 |
| 10 | 138355 |
| 11 | 655424 |
| 12 | 3121438 |
| 13 | 14930540 |
| 14 | 71675839 |
| 15 | 345148892 |
| 16 | 1666432816 |
| 17 | 8064278288 |
| 18 | 39103576699 |
| 19 | 189949958332 |
| 20 | 924163714216 |
| 21 | 4502711570988 |
| 22 | 21966152501239 |
| 23 | 107284324830302 |