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 | 3 |
| 2 | 12 |
| 3 | 52 |
| 4 | 228 |
| 5 | 969 |
| 6 | 3795 |
| 7 | 12285 |
| 8 | 19227 |
| 9 | -162316 |
| 10 | -2334219 |
| 11 | -20233746 |
| 12 | -146642814 |
| 13 | -956899038 |
| 14 | -5761740810 |
| 15 | -32172133140 |
| 16 | -164988072288 |
| 17 | -752632536117 |
| 18 | -2777949390584 |
| 19 | -5070274066512 |
| 20 | 41416739288496 |
| 21 | 663038498204040 |
| 22 | 6188361199762260 |
| 23 | 47738255512890555 |