find and return sequential numbers

I need to find sequential number in a row of random numbers and return those numbers separated by a comma or return a blank cell if no sequential numbers are found

For example

A1 | A2 | A3 | A4 | A5 | A6 | A7 |
23 17 19 20 42 74 19,20
45 23 27 36 83 48
13 14 42 46 78 18 13,14

Seems easy but I don't often use excel so I am lost....

Can the sequence be both decreasing or increasing sequentlally, i.e. is 14 13 12 as valid as 12 13 14? If so, what would your expected return be in a case like: 12 13 14 13 12?

increasing only... I am hoping that makes it a little easier?

Could still do with a bit more information. In your examples, you only have pairs of consecutive integers - are you interested in only these, or of consecutive sequences of any length, e.g. 2,3,4,5,6? And if there is more than one sequence found in the row, each sequence gets put into a separate cell, separated by commas?