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) |
|---|---|
| 1 | 3 |
| 2 | 18 |
| 3 | 84 |
| 4 | 468 |
| 5 | 2856 |
| 6 | 17800 |
| 7 | 110036 |
| 8 | 674984 |
| 9 | 4130664 |
| 10 | 25284068 |
| 11 | 154853080 |
| 12 | 948637896 |
| 13 | 5811528980 |
| 14 | 35601208264 |
| 15 | 218086661704 |
| 16 | 1335953081860 |
| 17 | 8183781374680 |
| 18 | 50132301702344 |
| 19 | 307101237458324 |
| 20 | 1881245567361512 |