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 | 4 |
| 3 | -10 |
| 4 | 23 |
| 5 | -59 |
| 6 | 138 |
| 7 | -340 |
| 8 | 813 |
| 9 | -1973 |
| 10 | 4752 |
| 11 | -11486 |
| 12 | 27715 |
| 13 | -66927 |
| 14 | 161558 |
| 15 | -390056 |
| 16 | 941657 |
| 17 | -2273385 |
| 18 | 5488412 |
| 19 | -13250226 |
| 20 | 31988847 |
| 21 | -77227939 |
| 22 | 186444706 |
| 23 | -450117372 |
| 24 | 1086679429 |
| 25 | -2623476253 |
| 26 | 6333631912 |
| 27 | -15290740102 |
| 28 | 36915112091 |
| 29 | -89120964311 |
| 30 | 215157040686 |
| 31 | -519435045712 |
| 32 | 1254027132081 |