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 | 15 |
| 4 | 76 |
| 5 | 785 |
| 6 | 7836 |
| 7 | 137263 |
| 8 | 2130976 |
| 9 | 47895489 |
| 10 | 1010012140 |
| 11 | 28531167071 |
| 12 | 743044702104 |
| 13 | 25239592216033 |
| 14 | 797785008119932 |
| 15 | 31147773583464735 |
| 16 | 1157442765678719056 |
| 17 | 51702516367896047777 |
| 18 | 2185932446984222457444 |
| 19 | 109912203092239643840239 |
| 20 | 5255987282125826560192520 |