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 | 1 |
| 3 | 0 |
| 4 | 1 |
| 5 | -2 |
| 6 | 5 |
| 7 | -12 |
| 8 | 28 |
| 9 | -63 |
| 10 | 137 |
| 11 | -290 |
| 12 | 604 |
| 13 | -1253 |
| 14 | 2617 |
| 15 | -5537 |
| 16 | 11870 |
| 17 | -25666 |
| 18 | 55617 |
| 19 | -120103 |
| 20 | 257582 |
| 21 | -548119 |
| 22 | 1158437 |
| 23 | -2437114 |
| 24 | 5117165 |
| 25 | -10748530 |
| 26 | 22621055 |
| 27 | -47728657 |
| 28 | 100932549 |
| 29 | -213750621 |
| 30 | 452855190 |
| 31 | -958925784 |
| 32 | 2028187595 |
| 33 | -4283531490 |
| 34 | 9033779224 |