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 | 4 |
| 2 | 18 |
| 3 | 56 |
| 4 | 190 |
| 5 | 564 |
| 6 | 1722 |
| 7 | 4976 |
| 8 | 14454 |
| 9 | 40940 |
| 10 | 115698 |
| 11 | 322728 |
| 12 | 896558 |
| 13 | 2471588 |
| 14 | 6786090 |
| 15 | 18537184 |
| 16 | 50459366 |
| 17 | 136844892 |
| 18 | 370030434 |
| 19 | 997705240 |
| 20 | 2683514526 |
| 21 | 7201203988 |
| 22 | 19284880794 |
| 23 | 51546789456 |
| 24 | 137541880150 |
| 25 | 366412976332 |