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 | 0 |
| 3 | 1 |
| 4 | 6 |
| 5 | 28 |
| 6 | 127 |
| 7 | 598 |
| 8 | 2984 |
| 9 | 15851 |
| 10 | 89532 |
| 11 | 536152 |
| 12 | 3392609 |
| 13 | 22609852 |
| 14 | 158220300 |
| 15 | 1159380201 |
| 16 | 8873605258 |
| 17 | 70778190768 |
| 18 | 587125257319 |
| 19 | 5055713850058 |
| 20 | 45114387675316 |
| 21 | 416535887361323 |
| 22 | 3973511993495144 |
| 23 | 39112086371684844 |