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 | 23 |
| 5 | 91 |
| 6 | 341 |
| 7 | 1221 |
| 8 | 4249 |
| 9 | 14465 |
| 10 | 48442 |
| 11 | 160134 |
| 12 | 523872 |
| 13 | 1699252 |
| 14 | 5472713 |
| 15 | 17520217 |
| 16 | 55801733 |
| 17 | 176942269 |
| 18 | 558906164 |
| 19 | 1759436704 |
| 20 | 5522119250 |
| 21 | 17285351782 |
| 22 | 53977433618 |
| 23 | 168194390290 |
| 24 | 523076690018 |
| 25 | 1623869984706 |