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 | 5 |
| 2 | 40 |
| 3 | 310 |
| 4 | 2395 |
| 5 | 18501 |
| 6 | 142920 |
| 7 | 1104060 |
| 8 | 8528890 |
| 9 | 65885880 |
| 10 | 508970002 |
| 11 | 3931805460 |
| 12 | 30373291380 |
| 13 | 234634403620 |
| 14 | 1812556389540 |
| 15 | 14002041536004 |
| 16 | 108166106338760 |
| 17 | 835585763004880 |
| 18 | 6454920038905520 |
| 19 | 49864411953151840 |
| 20 | 385203777033190008 |
| 21 | 2975708406629602400 |