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 | 3 |
| 4 | -8 |
| 5 | 25 |
| 6 | -82 |
| 7 | 279 |
| 8 | -974 |
| 9 | 3471 |
| 10 | -12582 |
| 11 | 46258 |
| 12 | -172092 |
| 13 | 646667 |
| 14 | -2450920 |
| 15 | 9358703 |
| 16 | -35970203 |
| 17 | 139053789 |
| 18 | -540332534 |
| 19 | 2109336474 |
| 20 | -8268739720 |
| 21 | 32536551783 |
| 22 | -128468095943 |
| 23 | 508841232024 |
| 24 | -2021249839308 |
| 25 | 8050245467461 |
| 26 | -32141168565845 |
| 27 | 128617254147007 |
| 28 | -515764830465583 |
| 29 | 2072316922422961 |
| 30 | -8341724250355787 |
| 31 | 33635614440282961 |
| 32 | -135843921900168936 |