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 | 3 |
| 2 | 9 |
| 3 | 27 |
| 4 | 121 |
| 5 | 403 |
| 6 | 1209 |
| 7 | 3627 |
| 8 | 14921 |
| 9 | 52803 |
| 10 | 162409 |
| 11 | 491227 |
| 12 | 2273721 |
| 13 | 7225203 |
| 14 | 22083609 |
| 15 | 106254827 |
| 16 | 319172521 |
| 17 | 957521603 |
| 18 | 2953364809 |
| 19 | 12940502427 |
| 20 | 42902311321 |
| 21 | 132707334003 |
| 22 | 402122410009 |
| 23 | 2010408030027 |
| 24 | 6031224090121 |
| 25 | 18093712270403 |
| 26 | 54285137211209 |