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 | 2 |
| 2 | 6 |
| 3 | 16 |
| 4 | 42 |
| 5 | 106 |
| 6 | 268 |
| 7 | 650 |
| 8 | 1580 |
| 9 | 3750 |
| 10 | 8862 |
| 11 | 20598 |
| 12 | 47776 |
| 13 | 109248 |
| 14 | 248966 |
| 15 | 562630 |
| 16 | 1264780 |
| 17 | 2823958 |
| 18 | 6282198 |
| 19 | 13884820 |
| 20 | 30590124 |
| 21 | 67051982 |
| 22 | 146463790 |
| 23 | 318588916 |
| 24 | 690882926 |
| 25 | 1492592450 |
| 26 | 3215372064 |
| 27 | 6904561416 |
| 28 | 14786529836 |
| 29 | 31574656096 |
| 30 | 67261524262 |