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 | 0 |
| 1 | 1 |
| 2 | 1 |
| 3 | 3 |
| 4 | 9 |
| 5 | 33 |
| 6 | 126 |
| 7 | 510 |
| 8 | 2127 |
| 9 | 9113 |
| 10 | 39809 |
| 11 | 176735 |
| 12 | 794937 |
| 13 | 3615045 |
| 14 | 16593156 |
| 15 | 76773972 |
| 16 | 357692784 |
| 17 | 1676664234 |
| 18 | 7901590287 |
| 19 | 37416151209 |
| 20 | 177935914254 |
| 21 | 849461877990 |
| 22 | 4069507806000 |
| 23 | 19557840481380 |
| 24 | 94267485120510 |
| 25 | 455575848843726 |
| 26 | 2207117072396682 |
| 27 | 10717034365197286 |