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 | 13 |
| 2 | 169 |
| 3 | 462 |
| 4 | 2446 |
| 5 | 11196 |
| 6 | 49442 |
| 7 | 231900 |
| 8 | 1070030 |
| 9 | 4844224 |
| 10 | 22421336 |
| 11 | 103071836 |
| 12 | 470766400 |
| 13 | 2169072096 |
| 14 | 9960748002 |
| 15 | 45637352134 |
| 16 | 209883232908 |
| 17 | 963579009422 |
| 18 | 4420355911200 |
| 19 | 20311365385702 |
| 20 | 93248420528358 |
| 21 | 427991086292782 |