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 | 3 |
| 3 | 11 |
| 4 | 42 |
| 5 | 153 |
| 6 | 469 |
| 7 | 690 |
| 8 | -5967 |
| 9 | -82708 |
| 10 | -700876 |
| 11 | -4989894 |
| 12 | -32082336 |
| 13 | -190742496 |
| 14 | -1053280998 |
| 15 | -5347579160 |
| 16 | -24162468390 |
| 17 | -88249158963 |
| 18 | -157067396045 |
| 19 | 1334548659436 |
| 20 | 20996875910808 |
| 21 | 194476989681546 |
| 22 | 1491599102987040 |
| 23 | 10232074769143770 |
| 24 | 64440205192609155 |