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 | 1 |
| 2 | 2056 |
| 3 | 177174 |
| 4 | 4210752 |
| 5 | 48828250 |
| 6 | 364269744 |
| 7 | 1977327086 |
| 8 | 8623620608 |
| 9 | 31385843307 |
| 10 | 100390882000 |
| 11 | 285311671942 |
| 12 | 746035774848 |
| 13 | 1792160396234 |
| 14 | 4065384488816 |
| 15 | 8651096365500 |
| 16 | 17661175009280 |
| 17 | 34271896312546 |
| 18 | 64529293839192 |
| 19 | 116490258905078 |
| 20 | 205603651344000 |
| 21 | 350330949134964 |