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 | 5 |
| 2 | 18 |
| 3 | 57 |
| 4 | 180 |
| 5 | 617 |
| 6 | 2400 |
| 7 | 10717 |
| 8 | 54544 |
| 9 | 312353 |
| 10 | 1988104 |
| 11 | 13921501 |
| 12 | 106350816 |
| 13 | 880162337 |
| 14 | 7844596536 |
| 15 | 74910367309 |
| 16 | 763030711936 |
| 17 | 8257927397569 |
| 18 | 94628877364936 |
| 19 | 1144609672707741 |
| 20 | 14573622985067744 |
| 21 | 194834987492011649 |
| 22 | 2728787718495477144 |
| 23 | 39955604972310966797 |