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 | 4 |
| 2 | 10 |
| 3 | 20 |
| 4 | 64 |
| 5 | 136 |
| 6 | 466 |
| 7 | 1012 |
| 8 | 3580 |
| 9 | 7864 |
| 10 | 28340 |
| 11 | 62696 |
| 12 | 228700 |
| 13 | 508400 |
| 14 | 1870466 |
| 15 | 4172660 |
| 16 | 15449740 |
| 17 | 34557400 |
| 18 | 128583340 |
| 19 | 288212440 |
| 20 | 1076603824 |
| 21 | 2417218544 |
| 22 | 9058241620 |
| 23 | 20366034760 |
| 24 | 76521687304 |
| 25 | 172247070064 |
| 26 | 648634854904 |