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) |
|---|---|
| 1 | 1 |
| 2 | 2 |
| 3 | 4 |
| 4 | 9 |
| 5 | 18 |
| 6 | 40 |
| 7 | 100 |
| 8 | 225 |
| 9 | 525 |
| 10 | 1225 |
| 11 | 3136 |
| 12 | 7056 |
| 13 | 17640 |
| 14 | 44100 |
| 15 | 108900 |
| 16 | 261360 |
| 17 | 637065 |
| 18 | 1656369 |
| 19 | 4008004 |
| 20 | 10020010 |
| 21 | 25050025 |
| 22 | 64128064 |
| 23 | 155739584 |
| 24 | 393853824 |
| 25 | 1012766976 |
| 26 | 2538950544 |
| 27 | 6347376360 |
| 28 | 15774544800 |
| 29 | 41408180100 |