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 | 55 |
| 2 | 595 |
| 3 | 990 |
| 4 | 5050 |
| 5 | 5995 |
| 6 | 500500 |
| 7 | 50005000 |
| 8 | 50909095 |
| 9 | 50999950 |
| 10 | 505000090 |
| 11 | 5000050000 |
| 12 | 500000500000 |
| 13 | 500999999500 |
| 14 | 955909595955 |
| 15 | 9055595509950 |
| 16 | 50000005000000 |
| 17 | 59000000095590 |
| 18 | 95595999550590 |
| 19 | 5000000050000000 |
| 20 | 5000990099009950 |
| 21 | 5000990999099095 |