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 | 0 |
| 2 | -2 |
| 3 | -9 |
| 4 | -33 |
| 5 | -113 |
| 6 | -376 |
| 7 | -1235 |
| 8 | -4032 |
| 9 | -13126 |
| 10 | -42673 |
| 11 | -138641 |
| 12 | -450293 |
| 13 | -1462292 |
| 14 | -4748343 |
| 15 | -15418256 |
| 16 | -50063514 |
| 17 | -162556377 |
| 18 | -527819057 |
| 19 | -1713820537 |
| 20 | -5564744720 |
| 21 | -18068619435 |
| 22 | -58668449392 |
| 23 | -190495275070 |
| 24 | -618534298433 |
| 25 | -2008368291137 |
| 26 | -6521130940157 |
| 27 | -21173979252396 |
| 28 | -68751478912175 |
| 29 | -223234649986656 |
| 30 | -724838355712626 |