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 | 3 |
| 3 | 63 |
| 4 | 1767 |
| 5 | 63690 |
| 6 | 2822740 |
| 7 | 148810032 |
| 8 | 9104502015 |
| 9 | 634448680884 |
| 10 | 49622704133175 |
| 11 | 4305280182748875 |
| 12 | 410376649359397380 |
| 13 | 42633179822414174760 |
| 14 | 4794685285831034253660 |
| 15 | 580373328155358031572600 |
| 16 | 75234419898396217903091151 |
| 17 | 10398952352945773993329785448 |
| 18 | 1526704288048697734221906020641 |