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 | 2 |
| 3 | 10 |
| 4 | 56 |
| 5 | 394 |
| 6 | 3332 |
| 7 | 32782 |
| 8 | 368072 |
| 9 | 4651666 |
| 10 | 65440748 |
| 11 | 1015205974 |
| 12 | 17225810768 |
| 13 | 317432262298 |
| 14 | 6313880504564 |
| 15 | 134828046043486 |
| 16 | 3076458785723864 |
| 17 | 74696205255843490 |
| 18 | 1922729345267645180 |
| 19 | 52297599798809376358 |
| 20 | 1498690940537194229600 |