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 | 3 |
| 2 | 8 |
| 3 | 120 |
| 4 | 637 |
| 5 | 2176 |
| 6 | 30848 |
| 7 | 164483 |
| 8 | 561288 |
| 9 | 7958776 |
| 10 | 42435837 |
| 11 | 144810240 |
| 12 | 2053333248 |
| 13 | 10948281603 |
| 14 | 37360480520 |
| 15 | 529752019320 |
| 16 | 2824614217597 |
| 17 | 9638859164032 |
| 18 | 136673967651200 |
| 19 | 728739519858563 |
| 20 | 2486788303839624 |
| 21 | 35261353901990392 |