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 | 0 |
| 4 | 5 |
| 5 | 18 |
| 6 | 89 |
| 7 | 519 |
| 8 | 3853 |
| 9 | 27555 |
| 10 | 233431 |
| 11 | 2167152 |
| 12 | 21596120 |
| 13 | 232817282 |
| 14 | 2718706924 |
| 15 | 33814848445 |
| 16 | 448311181346 |
| 17 | 6319365554730 |
| 18 | 94225534689624 |
| 19 | 1481940898130323 |
| 20 | 24536143182460549 |
| 21 | 426432943716156580 |
| 22 | 7762187693343502658 |
| 23 | 147704506384475066381 |