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 | 1 |
| 2 | 5 |
| 3 | 24 |
| 4 | 117 |
| 5 | 580 |
| 6 | 2916 |
| 7 | 14834 |
| 8 | 76221 |
| 9 | 395048 |
| 10 | 2063104 |
| 11 | 10847078 |
| 12 | 57373672 |
| 13 | 305110106 |
| 14 | 1630489090 |
| 15 | 8751851866 |
| 16 | 47166202181 |
| 17 | 255128842340 |
| 18 | 1384688987728 |
| 19 | 7538592535170 |
| 20 | 41159292861980 |
| 21 | 225315261459390 |
| 22 | 1236441650047554 |