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) |
|---|---|
| 1 | 0 |
| 2 | 0 |
| 3 | 1 |
| 4 | 4 |
| 5 | 20 |
| 6 | 86 |
| 7 | 409 |
| 8 | 1988 |
| 9 | 10404 |
| 10 | 57488 |
| 11 | 338180 |
| 12 | 2103378 |
| 13 | 13814202 |
| 14 | 95423766 |
| 15 | 691415451 |
| 16 | 5239857008 |
| 17 | 41431883216 |
| 18 | 341036489096 |
| 19 | 2916365967707 |
| 20 | 25862060748614 |
| 21 | 237434856965694 |
| 22 | 2253357681164288 |
| 23 | 22076002386446896 |
| 24 | 222979432604192844 |
| 25 | 2319295160051570620 |