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 | 4 |
| 4 | 18 |
| 5 | 88 |
| 6 | 360 |
| 7 | 1524 |
| 8 | 6090 |
| 9 | 24784 |
| 10 | 98244 |
| 11 | 393820 |
| 12 | 1556324 |
| 13 | 6196656 |
| 14 | 24461424 |
| 15 | 97079220 |
| 16 | 383132250 |
| 17 | 1518103840 |
| 18 | 5992343940 |
| 19 | 23726184372 |
| 20 | 93686670220 |
| 21 | 370840981680 |
| 22 | 1464969055368 |
| 23 | 5798679839524 |
| 24 | 22917832613988 |
| 25 | 90725318348448 |
| 26 | 358737952183800 |