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 | 1 |
| 2 | 2 |
| 3 | 8 |
| 4 | 54 |
| 5 | 533 |
| 6 | 6944 |
| 7 | 111850 |
| 8 | 2135740 |
| 9 | 47003045 |
| 10 | 1168832808 |
| 11 | 32363244260 |
| 12 | 986532609608 |
| 13 | 32810811179569 |
| 14 | 1181865951824800 |
| 15 | 45823912079507918 |
| 16 | 1902469319507438352 |
| 17 | 84195282530581058825 |
| 18 | 3956365033583165905568 |
| 19 | 196716723188140236180160 |