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 | 2 |
| 3 | 12 |
| 4 | 110 |
| 5 | 1274 |
| 6 | 17136 |
| 7 | 255816 |
| 8 | 4124406 |
| 9 | 70549050 |
| 10 | 1264752060 |
| 11 | 23555382240 |
| 12 | 452806924752 |
| 13 | 8939481277552 |
| 14 | 180551099694400 |
| 15 | 3719061442253520 |
| 16 | 77933728043586630 |
| 17 | 1658001861319441050 |
| 18 | 35749633305661575300 |
| 19 | 780123576993991461000 |
| 20 | 17208112644166765652100 |