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 | 1 |
| 2 | 3 |
| 3 | 11 |
| 4 | 50 |
| 5 | 257 |
| 6 | 1467 |
| 7 | 9081 |
| 8 | 60272 |
| 9 | 424514 |
| 10 | 3151226 |
| 11 | 24510411 |
| 12 | 198870388 |
| 13 | 1676878231 |
| 14 | 14648843341 |
| 15 | 132228263355 |
| 16 | 1230505582380 |
| 17 | 11782173683640 |
| 18 | 115878367974480 |
| 19 | 1168833058344870 |
| 20 | 12075008262774120 |
| 21 | 127608480923659770 |