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 | 3 |
| 3 | 9 |
| 4 | 33 |
| 5 | 135 |
| 6 | 633 |
| 7 | 3207 |
| 8 | 17588 |
| 9 | 102610 |
| 10 | 635800 |
| 11 | 4158270 |
| 12 | 28646346 |
| 13 | 206925540 |
| 14 | 1562928436 |
| 15 | 12295935458 |
| 16 | 100464068006 |
| 17 | 850030211990 |
| 18 | 7431638110124 |
| 19 | 67007477760634 |
| 20 | 622164698873152 |
| 21 | 5941062844925200 |
| 22 | 58280974293944802 |
| 23 | 586748859836258212 |
| 24 | 6056670347690677380 |