Talk:21 into 1/@comment-159.215.35.1-20150918191608/@comment-24234983-20150919184802

That's weird. If 9 was 6...

All the numbers you listed, except for 9, are triangular numbers.

Triangular numbers are somewhat interesting because the sum of the triangular numbers 1 through 21 is 1+3+6+10+15+21=56, which happens to be the number of key bits used by the DES block cipher. Maybe these six triangles need to be filled with binary bits from some source, and then arranged in some manner in order to form the decryption key. If we are looking at Triple DES, then we need three sets of six triangles to make up the 168 bits that are needed for a (three-key) Triple DES key. However, there is no obvious way how to fill these triangles with the bits, what to fill them with, how to manipulate the triangles and how to read out the bits again from them.