40bit decryption, pls help me to understand!

Hi,

I've a decrying challenge and I hope hashcat is the right tool to calculate keys or
helps me to understand how the keys are calculator.

I've some 40bit seed's and key's (real pairs) , how can use this pairs to get the unknown keys?

Example:
S: 4F 74 B9 8B 06       K: A1 FC 0F 7F 3E
S: 90 CB 24 29 06       K: 1D E7 55 89 7E
S: 12 34 56 78 06       K: 6A AC 56 C6 78
S: 00 02 03 01 06       K: ??  ??  ??  ??  ??

Is it possible to generate the algorithm to generate the key's and if yes, how?

Thx in advance
Joe