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 | 1 |
| 3 | 2 |
| 4 | 12 |
| 5 | 64 |
| 6 | 455 |
| 7 | 3618 |
| 8 | 33131 |
| 9 | 338728 |
| 10 | 3838572 |
| 11 | 47678520 |
| 12 | 644172045 |
| 13 | 9402091620 |
| 14 | 147405489205 |
| 15 | 2470129035710 |
| 16 | 44053120590540 |
| 17 | 833000495161600 |
| 18 | 16644648834503555 |
| 19 | 350406040769989974 |
| 20 | 7751328201878523295 |
| 21 | 179738821179613739780 |
| 22 | 4359334293132050359932 |
| 23 | 110368937036048741434824 |