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) |
|---|---|
| 5 | 1 |
| 6 | 15 |
| 7 | 140 |
| 8 | 1050 |
| 9 | 6951 |
| 10 | 42399 |
| 11 | 239800 |
| 12 | 1164570 |
| 13 | 2553551 |
| 14 | -54771717 |
| 15 | -1384474728 |
| 16 | -23286667950 |
| 17 | -339924740609 |
| 18 | -4554547609233 |
| 19 | -56481301888144 |
| 20 | -630768487283886 |
| 21 | -5665064764515849 |
| 22 | -18095553874845909 |
| 23 | 924820173031946752 |
| 24 | 35413415495503624986 |