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 | 0 |
| 3 | 1 |
| 4 | 9 |
| 5 | 91 |
| 6 | 993 |
| 7 | 12013 |
| 8 | 160275 |
| 9 | 2347141 |
| 10 | 37496163 |
| 11 | 649660573 |
| 12 | 12142311195 |
| 13 | 243626199181 |
| 14 | 5224710549243 |
| 15 | 119294328993853 |
| 16 | 2889836999693355 |
| 17 | 74037381200415901 |
| 18 | 2000383612949821323 |
| 19 | 56850708386783835133 |
| 20 | 1695491518035158123115 |
| 21 | 52949018580275965241821 |