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 | -2 |
| 2 | -1 |
| 3 | -5 |
| 4 | -32 |
| 5 | -253 |
| 6 | -2381 |
| 7 | -25912 |
| 8 | -319339 |
| 9 | -4388949 |
| 10 | -66495386 |
| 11 | -1100521327 |
| 12 | -19751191053 |
| 13 | -382062458174 |
| 14 | -7924762051957 |
| 15 | -175478462117633 |
| 16 | -4132047373455024 |
| 17 | -103115456926017761 |
| 18 | -2718766185148876961 |
| 19 | -75529218928863243200 |
| 20 | -2205316818199975235447 |