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 | 2 |
| 3 | 4 |
| 4 | 8 |
| 5 | 20 |
| 6 | 52 |
| 7 | 140 |
| 8 | 400 |
| 9 | 1203 |
| 10 | 3808 |
| 11 | 12634 |
| 12 | 43771 |
| 13 | 157821 |
| 14 | 590518 |
| 15 | 2287070 |
| 16 | 9148286 |
| 17 | 37719353 |
| 18 | 160029667 |
| 19 | 697553152 |
| 20 | 3119552536 |
| 21 | 14295585635 |
| 22 | 67052240163 |
| 23 | 321571247089 |
| 24 | 1575370942644 |
| 25 | 7876854713228 |
| 26 | 40164235888490 |
| 27 | 208699491618146 |
| 28 | 1104333907134455 |
| 29 | 5947020092025820 |