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 | 4 |
| 3 | 25 |
| 4 | 120 |
| 5 | 497 |
| 6 | 1924 |
| 7 | 7265 |
| 8 | 27288 |
| 9 | 102745 |
| 10 | 388692 |
| 11 | 1477721 |
| 12 | 5643064 |
| 13 | 21632785 |
| 14 | 83204260 |
| 15 | 320932177 |
| 16 | 1240939448 |
| 17 | 4808642313 |
| 18 | 18668848852 |
| 19 | 72601081385 |
| 20 | 282762109272 |
| 21 | 1102772229313 |
| 22 | 4306062994148 |
| 23 | 16832791708257 |
| 24 | 65867445819160 |
| 25 | 257980829463017 |