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 | 1 |
| 2 | 1 |
| 3 | 4 |
| 4 | 17 |
| 5 | 81 |
| 6 | 412 |
| 7 | 2192 |
| 8 | 12049 |
| 9 | 67891 |
| 10 | 390041 |
| 11 | 2276176 |
| 12 | 13455356 |
| 13 | 80402284 |
| 14 | 484865032 |
| 15 | 2947107384 |
| 16 | 18036248337 |
| 17 | 111046920567 |
| 18 | 687345582787 |
| 19 | 4274642610932 |
| 20 | 26697307240777 |
| 21 | 167377288848977 |