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 | 0 |
| 2 | 3 |
| 3 | -2 |
| 4 | 9 |
| 5 | -12 |
| 6 | 31 |
| 7 | -54 |
| 8 | 117 |
| 9 | -224 |
| 10 | 459 |
| 11 | -906 |
| 12 | 1825 |
| 13 | -3636 |
| 14 | 7287 |
| 15 | -14558 |
| 16 | 29133 |
| 17 | -58248 |
| 18 | 116515 |
| 19 | -233010 |
| 20 | 466041 |
| 21 | -932060 |
| 22 | 1864143 |
| 23 | -3728262 |
| 24 | 7456549 |
| 25 | -14913072 |
| 26 | 29826171 |
| 27 | -59652314 |
| 28 | 119304657 |
| 29 | -238609284 |
| 30 | 477218599 |
| 31 | -954437166 |
| 32 | 1908874365 |
| 33 | -3817748696 |
| 34 | 7635497427 |