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 | 1 |
| 2 | 2 |
| 3 | 4 |
| 4 | 12 |
| 5 | 22 |
| 6 | 68 |
| 7 | 166 |
| 8 | 534 |
| 9 | 1589 |
| 10 | 5464 |
| 11 | 18579 |
| 12 | 68320 |
| 13 | 255424 |
| 14 | 1000852 |
| 15 | 4018156 |
| 16 | 16671976 |
| 17 | 70890940 |
| 18 | 309439942 |
| 19 | 1381815168 |
| 20 | 6310880471 |
| 21 | 29428287639 |
| 22 | 140012980007 |
| 23 | 678970863717 |
| 24 | 3353545264060 |
| 25 | 16857749613964 |
| 26 | 86191265140699 |
| 27 | 447951112379963 |
| 28 | 2365177154077186 |