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 | 5 |
| 3 | 40 |
| 4 | 437 |
| 5 | 6036 |
| 6 | 100657 |
| 7 | 1965160 |
| 8 | 43937385 |
| 9 | 1106488720 |
| 10 | 30982333661 |
| 11 | 954607270464 |
| 12 | 32090625710365 |
| 13 | 1168646120904640 |
| 14 | 45826588690845705 |
| 15 | 1924996299465966976 |
| 16 | 86231288506425806033 |
| 17 | 4103067277186778016000 |
| 18 | 206655307175847710248885 |