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 | -4 |
| 2 | 15 |
| 3 | -53 |
| 4 | 178 |
| 5 | -575 |
| 6 | 1809 |
| 7 | -5598 |
| 8 | 17141 |
| 9 | -52113 |
| 10 | 157724 |
| 11 | -475997 |
| 12 | 1433429 |
| 13 | -4311364 |
| 14 | 12958627 |
| 15 | -38909601 |
| 16 | 116831426 |
| 17 | -350844883 |
| 18 | 1051414421 |
| 19 | -3160120038 |
| 20 | 9491592177 |
| 21 | -28218244109 |
| 22 | 86403627444 |
| 23 | -255153772169 |
| 24 | 722619907385 |
| 25 | -2772952748516 |
| 26 | 4627276967623 |
| 27 | -17420488524253 |