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 | 20 |
| 2 | 255 |
| 3 | 2650 |
| 4 | 24521 |
| 5 | 210840 |
| 6 | 1725234 |
| 7 | 13631700 |
| 8 | 104993955 |
| 9 | 793367300 |
| 10 | 5907885412 |
| 11 | 43495473840 |
| 12 | 317355930255 |
| 13 | 2298888740400 |
| 14 | 16555878011448 |
| 15 | 118661449810320 |
| 16 | 847132614218907 |
| 17 | 6027874235210700 |
| 18 | 42773816956415055 |
| 19 | 302816249208061050 |
| 20 | 2139537520524710691 |