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 | 8 |
| 3 | 56 |
| 4 | 456 |
| 5 | 3640 |
| 6 | 29128 |
| 7 | 233016 |
| 8 | 1864136 |
| 9 | 14913080 |
| 10 | 119304648 |
| 11 | 954437176 |
| 12 | 7635497416 |
| 13 | 61083979320 |
| 14 | 488671834568 |
| 15 | 3909374676536 |
| 16 | 31274997412296 |
| 17 | 250199979298360 |
| 18 | 2001599834386888 |
| 19 | 16012798675095096 |
| 20 | 128102389400760776 |
| 21 | 1024819115206086200 |
| 22 | 8198552921648689608 |