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 | 15 |
| 3 | -5 |
| 4 | 191 |
| 5 | 99 |
| 6 | 2455 |
| 7 | 3515 |
| 8 | 33231 |
| 9 | 74899 |
| 10 | 474695 |
| 11 | 1371435 |
| 12 | 7071871 |
| 13 | 23520899 |
| 14 | 108399735 |
| 15 | 390617755 |
| 16 | 1691480111 |
| 17 | 6378762099 |
| 18 | 26676785575 |
| 19 | 103221406475 |
| 20 | 423343881951 |
| 21 | 1661998662499 |
| 22 | 6742129440215 |
| 23 | 26686105001595 |
| 24 | 107591675061391 |
| 25 | 427824901526099 |
| 26 | 1718925069371655 |