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 | 1 |
| 1 | 0 |
| 2 | 1 |
| 3 | 1 |
| 4 | 15 |
| 5 | 158 |
| 6 | 3355 |
| 7 | 93708 |
| 8 | 3535448 |
| 9 | 170816680 |
| 10 | 10307577384 |
| 11 | 759439940230 |
| 12 | 67095584693434 |
| 13 | 7001532238614324 |
| 14 | 851997581131397870 |
| 15 | 119582892039683711842 |
| 16 | 19176016845387328919910 |
| 17 | 3484133398830462852182192 |
| 18 | 712017802878894004029129622 |
| 19 | 162597177988359237252433594350 |