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 | 0 |
| 1 | 1 |
| 2 | 0 |
| 3 | 3 |
| 4 | -1 |
| 5 | 10 |
| 6 | -7 |
| 7 | 35 |
| 8 | -36 |
| 9 | 127 |
| 10 | -165 |
| 11 | 474 |
| 12 | -715 |
| 13 | 1807 |
| 14 | -3004 |
| 15 | 6995 |
| 16 | -12393 |
| 17 | 27370 |
| 18 | -50559 |
| 19 | 107883 |
| 20 | -204820 |
| 21 | 427351 |
| 22 | -826045 |
| 23 | 1698458 |
| 24 | -3321891 |
| 25 | 6765175 |
| 26 | -13333932 |
| 27 | 26985675 |
| 28 | -53457121 |
| 29 | 107746282 |
| 30 | -214146295 |
| 31 | 430470899 |
| 32 | -857417220 |
| 33 | 1720537327 |
| 34 | -3431847189 |