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 | 3 |
| 3 | -7 |
| 4 | 15 |
| 5 | -35 |
| 6 | 79 |
| 7 | -179 |
| 8 | 407 |
| 9 | -923 |
| 10 | 2095 |
| 11 | -4755 |
| 12 | 10791 |
| 13 | -24491 |
| 14 | 55583 |
| 15 | -126147 |
| 16 | 286295 |
| 17 | -649755 |
| 18 | 1474639 |
| 19 | -3346739 |
| 20 | 7595527 |
| 21 | -17238283 |
| 22 | 39122815 |
| 23 | -88790435 |
| 24 | 201512631 |
| 25 | -457339131 |
| 26 | 1037945263 |
| 27 | -2355648787 |
| 28 | 5346217575 |
| 29 | -12133405675 |
| 30 | 27537138399 |
| 31 | -62496384899 |
| 32 | 141837473047 |