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 | 0 |
| 1 | 1 |
| 2 | -1 |
| 3 | 4 |
| 4 | -5 |
| 5 | 15 |
| 6 | -22 |
| 7 | 57 |
| 8 | -93 |
| 9 | 220 |
| 10 | -385 |
| 11 | 859 |
| 12 | -1574 |
| 13 | 3381 |
| 14 | -6385 |
| 15 | 13380 |
| 16 | -25773 |
| 17 | 53143 |
| 18 | -103702 |
| 19 | 211585 |
| 20 | -416405 |
| 21 | 843756 |
| 22 | -1669801 |
| 23 | 3368259 |
| 24 | -6690150 |
| 25 | 13455325 |
| 26 | -26789257 |
| 27 | 53774932 |
| 28 | -107232053 |
| 29 | 214978335 |
| 30 | -429124630 |
| 31 | 859595529 |
| 32 | -1717012749 |
| 33 | 3437550076 |