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 | 40 |
| 3 | 388 |
| 4 | 3472 |
| 5 | 29644 |
| 6 | 246520 |
| 7 | 2019028 |
| 8 | 16386592 |
| 9 | 132264604 |
| 10 | 1063976200 |
| 11 | 8541106468 |
| 12 | 68475336112 |
| 13 | 548535110764 |
| 14 | 4391942995480 |
| 15 | 35153854510708 |
| 16 | 281322388820032 |
| 17 | 2251036874232124 |
| 18 | 18010583812216360 |
| 19 | 144096114589527748 |