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) |
|---|---|
| 2 | 1 |
| 3 | 5 |
| 4 | 31 |
| 5 | 218 |
| 6 | 1658 |
| 7 | 13293 |
| 8 | 110675 |
| 9 | 947870 |
| 10 | 8297926 |
| 11 | 73924162 |
| 12 | 668038006 |
| 13 | 6108962580 |
| 14 | 56426393268 |
| 15 | 525673683069 |
| 16 | 4933634156571 |
| 17 | 46604425575734 |
| 18 | 442753710351950 |
| 19 | 4227598589181750 |
| 20 | 40549714320544770 |
| 21 | 390522305786747820 |