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 | 0 |
| 2 | 2 |
| 3 | 3 |
| 4 | 10 |
| 5 | 30 |
| 6 | 77 |
| 7 | 252 |
| 8 | 682 |
| 9 | 2145 |
| 10 | 6182 |
| 11 | 18887 |
| 12 | 56317 |
| 13 | 170534 |
| 14 | 515930 |
| 15 | 1563843 |
| 16 | 4759338 |
| 17 | 14480073 |
| 18 | 44203595 |
| 19 | 134972504 |
| 20 | 412984510 |
| 21 | 1264601502 |
| 22 | 3877302717 |
| 23 | 11898761051 |
| 24 | 36548512477 |
| 25 | 112358685555 |
| 26 | 345673541514 |
| 27 | 1064250223230 |
| 28 | 3278695047218 |
| 29 | 10107173174013 |
| 30 | 31174889414807 |