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 | 0 |
| 2 | 10 |
| 3 | 48 |
| 4 | 190 |
| 5 | 720 |
| 6 | 2698 |
| 7 | 10080 |
| 8 | 37630 |
| 9 | 140448 |
| 10 | 524170 |
| 11 | 1956240 |
| 12 | 7300798 |
| 13 | 27246960 |
| 14 | 101687050 |
| 15 | 379501248 |
| 16 | 1416317950 |
| 17 | 5285770560 |
| 18 | 19726764298 |
| 19 | 73621286640 |
| 20 | 274758382270 |
| 21 | 1025412242448 |
| 22 | 3826890587530 |
| 23 | 14282150107680 |
| 24 | 53301709843198 |
| 25 | 198924689265120 |