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 | 5 |
| 3 | 14 |
| 4 | 37 |
| 5 | 34 |
| 6 | -887 |
| 7 | -14050 |
| 8 | -168919 |
| 9 | -1916542 |
| 10 | -21607859 |
| 11 | -245387858 |
| 12 | -2799384755 |
| 13 | -31558843486 |
| 14 | -337767590383 |
| 15 | -3063846770626 |
| 16 | -11912361112367 |
| 17 | 477367592119810 |
| 18 | 21032925955607701 |
| 19 | 627398853149961038 |
| 20 | 16703816669710968821 |