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 | 20 |
| 3 | 96 |
| 4 | 436 |
| 5 | 1880 |
| 6 | 7836 |
| 7 | 32032 |
| 8 | 129572 |
| 9 | 521256 |
| 10 | 2091052 |
| 11 | 8376368 |
| 12 | 33529908 |
| 13 | 134168632 |
| 14 | 536772668 |
| 15 | 2147287104 |
| 16 | 8589541444 |
| 17 | 34358952008 |
| 18 | 137437380684 |
| 19 | 549752668240 |
| 20 | 2199016964180 |
| 21 | 8796080439384 |
| 22 | 35184346923100 |
| 23 | 140737438023776 |