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 | 1 |
| 2 | 2 |
| 3 | 4 |
| 4 | 5 |
| 5 | -13 |
| 6 | -147 |
| 7 | -816 |
| 8 | -3534 |
| 9 | -12650 |
| 10 | -35420 |
| 11 | -53040 |
| 12 | 199056 |
| 13 | 2391340 |
| 14 | 14555740 |
| 15 | 68264112 |
| 16 | 261045693 |
| 17 | 769660569 |
| 18 | 1167906402 |
| 19 | -5145668100 |
| 20 | -61758940705 |
| 21 | -385813067255 |
| 22 | -1857144860445 |
| 23 | -7266981925560 |
| 24 | -21793022441775 |
| 25 | -32643056947527 |
| 26 | 161919845140752 |