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 | 5 |
| 2 | 23 |
| 3 | 103 |
| 4 | 457 |
| 5 | 2021 |
| 6 | 8927 |
| 7 | 39415 |
| 8 | 174001 |
| 9 | 768101 |
| 10 | 3390599 |
| 11 | 14966887 |
| 12 | 66067129 |
| 13 | 291634565 |
| 14 | 1287337487 |
| 15 | 5682582967 |
| 16 | 25084135393 |
| 17 | 110726731589 |
| 18 | 488771441783 |
| 19 | 2157541529575 |
| 20 | 9523849084969 |
| 21 | 42040303802789 |