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 | 1 |
| 3 | 2 |
| 4 | 4 |
| 5 | 9 |
| 6 | 21 |
| 7 | 56 |
| 8 | 155 |
| 9 | 469 |
| 10 | 1480 |
| 11 | 4882 |
| 12 | 16545 |
| 13 | 57384 |
| 14 | 202060 |
| 15 | 720526 |
| 16 | 2593494 |
| 17 | 9408469 |
| 18 | 34350507 |
| 19 | 126109784 |
| 20 | 465200333 |
| 21 | 1723346074 |
| 22 | 6408356210 |
| 23 | 23911272090 |
| 24 | 89495909409 |
| 25 | 335916761128 |
| 26 | 1264114452996 |
| 27 | 4768464309416 |
| 28 | 18027250459483 |
| 29 | 68291947831046 |
| 30 | 259200707489634 |