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) |
|---|---|
| 1 | 24 |
| 2 | 220 |
| 3 | 504 |
| 4 | 0 |
| 5 | 15010 |
| 6 | 142692 |
| 7 | 340660 |
| 8 | 0 |
| 9 | 10924220 |
| 10 | 105606040 |
| 11 | 255768620 |
| 12 | 0 |
| 13 | 8472842700 |
| 14 | 82602700388 |
| 15 | 201570991218 |
| 16 | 0 |
| 17 | 6800283132780 |
| 18 | 66634056364880 |
| 19 | 163360889824230 |
| 20 | 0 |
| 21 | 5575911122723700 |
| 22 | 54822111009651480 |
| 23 | 134826580792851780 |