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 | 4 |
| 3 | 20 |
| 4 | 276 |
| 5 | 4324 |
| 6 | 229348 |
| 7 | 13535280 |
| 8 | 3023313284 |
| 9 | 745416341496 |
| 10 | 730044829512632 |
| 11 | 786671485270308848 |
| 12 | 3452664855804347354220 |
| 13 | 16652005717670534681315580 |
| 14 | 331809088406733654427925292528 |
| 15 | 7263611367960266490262600117251524 |