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 | 16 |
| 3 | 65 |
| 4 | 264 |
| 5 | 1072 |
| 6 | 4353 |
| 7 | 17676 |
| 8 | 71776 |
| 9 | 291457 |
| 10 | 1183504 |
| 11 | 4805792 |
| 12 | 19514625 |
| 13 | 79242004 |
| 14 | 321773808 |
| 15 | 1306609857 |
| 16 | 5305681432 |
| 17 | 21544499536 |
| 18 | 87484608001 |
| 19 | 355244113436 |
| 20 | 1442520953280 |
| 21 | 5857568421121 |
| 22 | 23785517797920 |
| 23 | 96584592144960 |
| 24 | 392195937000961 |