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 | 1 |
| 2 | 1 |
| 3 | 2 |
| 4 | 12 |
| 5 | 57 |
| 6 | 366 |
| 7 | 2340 |
| 8 | 16252 |
| 9 | 115940 |
| 10 | 854981 |
| 11 | 6444826 |
| 12 | 49554420 |
| 13 | 387203390 |
| 14 | 3068067060 |
| 15 | 24604111560 |
| 16 | 199398960212 |
| 17 | 1631041938108 |
| 18 | 13451978877748 |
| 19 | 111765327780200 |
| 20 | 934774244822704 |
| 21 | 7865200653146905 |