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 | 1 |
| 2 | 3 |
| 3 | 12 |
| 4 | 45 |
| 5 | 162 |
| 6 | 567 |
| 7 | 1944 |
| 8 | 6561 |
| 9 | 21870 |
| 10 | 72171 |
| 11 | 236196 |
| 12 | 767637 |
| 13 | 2480058 |
| 14 | 7971615 |
| 15 | 25509168 |
| 16 | 81310473 |
| 17 | 258280326 |
| 18 | 817887699 |
| 19 | 2582803260 |
| 20 | 8135830269 |
| 21 | 25569752274 |
| 22 | 80196041223 |
| 23 | 251048476872 |
| 24 | 784526490225 |
| 25 | 2447722649502 |