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 | 1 |
| 2 | 3 |
| 3 | 9 |
| 4 | 24 |
| 5 | 42 |
| 6 | -87 |
| 7 | -1575 |
| 8 | -12240 |
| 9 | -77730 |
| 10 | -449994 |
| 11 | -2470278 |
| 12 | -13101228 |
| 13 | -67823484 |
| 14 | -344888619 |
| 15 | -1729791975 |
| 16 | -8581375224 |
| 17 | -42194252106 |
| 18 | -205940062998 |
| 19 | -998899022898 |
| 20 | -4819339232640 |
| 21 | -23144643733428 |
| 22 | -110703908388582 |
| 23 | -527633003316726 |
| 24 | -2506857120078336 |