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 | 1 |
| 2 | 4 |
| 3 | 15 |
| 4 | 61 |
| 5 | 249 |
| 6 | 1040 |
| 7 | 4363 |
| 8 | 18424 |
| 9 | 78014 |
| 10 | 331099 |
| 11 | 1407080 |
| 12 | 5985505 |
| 13 | 25477399 |
| 14 | 108493103 |
| 15 | 462147381 |
| 16 | 1969025286 |
| 17 | 8390475609 |
| 18 | 35757524184 |
| 19 | 152398429323 |
| 20 | 649555719160 |
| 21 | 2768653475487 |
| 22 | 11801369554033 |
| 23 | 50304231997727 |
| 24 | 214428538858889 |
| 25 | 914039405714237 |