More friendly numbers

In an earlier blog I had shown how the numbers 13 and 16 can be treated as friends.These 2 numbers are in fact a particular version of a general case of friendship.The friendship I suggest is between the digits 4 and 7.Details are as follows. You can take any number like 25 or 34 where the sum of the digits is 7.Work out the squares-giving us 625 and 1156.Add the digits of these two you will get 4....6+2+5=13and 1+3=4.Likewise 1+1+5+6=13 and 1+3=4.Similarly take any  number like 31 and 22 where the sum of the digits is 4.Square and add the digits.You will have 7 as the result.....,31*31=961....9+6+1=16  and 1+6=7....22*22=484  4+8+4=16 and 1+6=7.
You can take any number with as many digits as you like where the sum of the digits is 4 or 7.The friendship will be revealed in every case.
Some more cases of friendship will follow