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) |
|---|---|
| 1 | 1 |
| 2 | 1 |
| 3 | 0 |
| 4 | -4 |
| 5 | 2 |
| 6 | 52 |
| 7 | -96 |
| 8 | -975 |
| 9 | 4240 |
| 10 | 18460 |
| 11 | -183448 |
| 12 | -101716 |
| 13 | 7373216 |
| 14 | -23650520 |
| 15 | -230147920 |
| 16 | 2198499720 |
| 17 | 664806792 |
| 18 | -124144328784 |
| 19 | 703989911368 |
| 20 | 3189500786336 |
| 21 | -68800373946656 |
| 22 | 284782780974128 |
| 23 | 2913071885553608 |
| 24 | -47063844278787824 |
| 25 | 170357147598919640 |
| 26 | 2621783446017272624 |
| 27 | -41775596442709927664 |
| 28 | 166446909354828214608 |