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 | 2 |
| 2 | 7 |
| 3 | 28 |
| 4 | 118 |
| 5 | 510 |
| 6 | 2235 |
| 7 | 9876 |
| 8 | 43870 |
| 9 | 195556 |
| 10 | 873814 |
| 11 | 3911168 |
| 12 | 17527904 |
| 13 | 78622982 |
| 14 | 352911939 |
| 15 | 1584927828 |
| 16 | 7120769526 |
| 17 | 32002212252 |
| 18 | 143859840114 |
| 19 | 646819996008 |
| 20 | 2908670252676 |
| 21 | 13081556909292 |
| 22 | 58839348572574 |
| 23 | 264674150692488 |
| 24 | 1190649451348908 |
| 25 | 5356483791828840 |
| 26 | 24098774900561500 |