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 | 3 |
| 2 | 8 |
| 3 | 25 |
| 4 | 87 |
| 5 | 386 |
| 6 | 1663 |
| 7 | 11313 |
| 8 | 39560 |
| 9 | 717067 |
| 10 | -2408199 |
| 11 | 128675438 |
| 12 | -2009225567 |
| 13 | 53624676795 |
| 14 | -1282589050168 |
| 15 | 35660396328721 |
| 16 | -1032462831852297 |
| 17 | 32302377782200418 |
| 18 | -1070227545188815745 |
| 19 | 37651172275242136857 |
| 20 | -1398665563931458389304 |
| 21 | 54757245858874447661683 |