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 | 4 |
| 3 | 3 |
| 4 | 35 |
| 5 | 112 |
| 6 | 533 |
| 7 | 2163 |
| 8 | 9316 |
| 9 | 39215 |
| 10 | 166519 |
| 11 | 704736 |
| 12 | 2986361 |
| 13 | 12648727 |
| 14 | 53583620 |
| 15 | 226979403 |
| 16 | 961507387 |
| 17 | 4072998992 |
| 18 | 17253519469 |
| 19 | 73087050795 |
| 20 | 309601764836 |
| 21 | 1311494041879 |
| 22 | 5555578042799 |
| 23 | 23533806034368 |
| 24 | 99690802469425 |
| 25 | 422297015444207 |