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 | 3 |
| 2 | 18 |
| 3 | 146 |
| 4 | 1510 |
| 5 | 19302 |
| 6 | 296520 |
| 7 | 5339924 |
| 8 | 110447046 |
| 9 | 2581169510 |
| 10 | 67274981356 |
| 11 | 1934941601628 |
| 12 | 60878718397276 |
| 13 | 2080009638726684 |
| 14 | 76694241037743300 |
| 15 | 3035502492679964520 |
| 16 | 128364744764608411718 |
| 17 | 5776084128332328033798 |
| 18 | 275565308510875579650348 |