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 | 1 |
| 2 | 4 |
| 3 | 26 |
| 4 | 260 |
| 5 | 3368 |
| 6 | 53744 |
| 7 | 1022320 |
| 8 | 22522960 |
| 9 | 565532992 |
| 10 | 15915225216 |
| 11 | 496911749920 |
| 12 | 17029582652416 |
| 13 | 636101065346560 |
| 14 | 25705530908501760 |
| 15 | 1118038500044633088 |
| 16 | 52054862490790200576 |
| 17 | 2584158975023147147264 |