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 | -2 |
| 1 | -1 |
| 2 | 1 |
| 3 | 6 |
| 4 | 19 |
| 5 | 53 |
| 6 | 142 |
| 7 | 375 |
| 8 | 985 |
| 9 | 2582 |
| 10 | 6763 |
| 11 | 17709 |
| 12 | 46366 |
| 13 | 121391 |
| 14 | 317809 |
| 15 | 832038 |
| 16 | 2178307 |
| 17 | 5702885 |
| 18 | 14930350 |
| 19 | 39088167 |
| 20 | 102334153 |
| 21 | 267914294 |
| 22 | 701408731 |
| 23 | 1836311901 |
| 24 | 4807526974 |
| 25 | 12586269023 |
| 26 | 32951280097 |
| 27 | 86267571270 |
| 28 | 225851433715 |
| 29 | 591286729877 |