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 | 3 |
| 4 | 19 |
| 5 | 141 |
| 6 | 1180 |
| 7 | 10593 |
| 8 | 99712 |
| 9 | 971067 |
| 10 | 9702388 |
| 11 | 98899638 |
| 12 | 1024429861 |
| 13 | 10752006033 |
| 14 | 114097140757 |
| 15 | 1222113460332 |
| 16 | 13195550763793 |
| 17 | 143470913825427 |
| 18 | 1569448022488435 |
| 19 | 17261100136608984 |
| 20 | 190752895126918819 |