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 | 4 |
| 2 | 15 |
| 3 | 58 |
| 4 | 241 |
| 5 | 1056 |
| 6 | 4879 |
| 7 | 23710 |
| 8 | 120033 |
| 9 | 635356 |
| 10 | 3478351 |
| 11 | 19796514 |
| 12 | 115988305 |
| 13 | 703052728 |
| 14 | 4372581711 |
| 15 | 28022140486 |
| 16 | 183804777409 |
| 17 | 1238244635700 |
| 18 | 8520907808143 |
| 19 | 60061024788106 |
| 20 | 431735704061361 |
| 21 | 3171780156493264 |
| 22 | 23730347517489295 |
| 23 | 181115025566445678 |