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 | 4 |
| 2 | 26 |
| 3 | 156 |
| 4 | 939 |
| 5 | 5764 |
| 6 | 36248 |
| 7 | 233900 |
| 8 | 1549193 |
| 9 | 10529052 |
| 10 | 73390856 |
| 11 | 524300728 |
| 12 | 3836318617 |
| 13 | 28731858368 |
| 14 | 220121136396 |
| 15 | 1724083566552 |
| 16 | 13798004944813 |
| 17 | 112773980097516 |
| 18 | 940841899662784 |
| 19 | 8008011665402152 |
| 20 | 69505777613953576 |