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 | 8 |
| 3 | 57 |
| 4 | 384 |
| 5 | 2505 |
| 6 | 16008 |
| 7 | 100849 |
| 8 | 628736 |
| 9 | 3888657 |
| 10 | 23900040 |
| 11 | 146146473 |
| 12 | 889928064 |
| 13 | 5399971161 |
| 14 | 32668236552 |
| 15 | 197123362785 |
| 16 | 1186790473728 |
| 17 | 7131032334369 |
| 18 | 42773183020296 |
| 19 | 256161548120857 |
| 20 | 1531966218561920 |
| 21 | 9150330147133161 |
| 22 | 54591847064667528 |
| 23 | 325361790187810257 |