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 | 4 |
| 2 | 9 |
| 3 | 33 |
| 4 | 213 |
| 5 | 2315 |
| 6 | 30031 |
| 7 | 510515 |
| 8 | 9699691 |
| 9 | 223092871 |
| 10 | 6469693233 |
| 11 | 200560490134 |
| 12 | 7420738134814 |
| 13 | 304250263527221 |
| 14 | 13082761331670031 |
| 15 | 614889782588491414 |
| 16 | 32589158477190044737 |
| 17 | 1922760350154212639074 |
| 18 | 117288381359406970983271 |
| 19 | 7858321551080267055879091 |