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 | 3 |
| 1 | 22 |
| 2 | 111 |
| 3 | 474 |
| 4 | 1836 |
| 5 | 6666 |
| 6 | 23109 |
| 7 | 77378 |
| 8 | 252177 |
| 9 | 804228 |
| 10 | 2519640 |
| 11 | 7777860 |
| 12 | 23709783 |
| 13 | 71501422 |
| 14 | 213619683 |
| 15 | 633011454 |
| 16 | 1862264196 |
| 17 | 5443487406 |
| 18 | 15820188729 |
| 19 | 45739697306 |
| 20 | 131624104677 |
| 21 | 377157259848 |