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 | 7 |
| 3 | 20 |
| 4 | 54 |
| 5 | 147 |
| 6 | 400 |
| 7 | 1085 |
| 8 | 2947 |
| 9 | 8000 |
| 10 | 21715 |
| 11 | 58944 |
| 12 | 160000 |
| 13 | 434306 |
| 14 | 1178890 |
| 15 | 3200000 |
| 16 | 8686136 |
| 17 | 23577801 |
| 18 | 64000000 |
| 19 | 173722727 |
| 20 | 471556031 |
| 21 | 1280000000 |
| 22 | 3474454549 |
| 23 | 9431120636 |
| 24 | 25600000000 |
| 25 | 69489090984 |
| 26 | 188622412730 |
| 27 | 512000000000 |
| 28 | 1389781819696 |