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 | 15 |
| 3 | 57 |
| 4 | 216 |
| 5 | 819 |
| 6 | 3105 |
| 7 | 11772 |
| 8 | 44631 |
| 9 | 169209 |
| 10 | 641520 |
| 11 | 2432187 |
| 12 | 9221121 |
| 13 | 34959924 |
| 14 | 132543135 |
| 15 | 502509177 |
| 16 | 1905156936 |
| 17 | 7222998339 |
| 18 | 27384465825 |
| 19 | 103822392492 |
| 20 | 393620574951 |
| 21 | 1492328902329 |
| 22 | 5657848431840 |
| 23 | 21450532002507 |