how to use the decoded raw value to send IR signal in arduino I am IR library from Ken Shirrif at https://github.com/z3t0/Arduino-IRremote/releases/download/MAJOR/IRremote.zip

It is good and I have used the examples to receive and send and to playback IR signals from the library. And they are working good.

To send Unknown signals we should use sendRaw() method with a list of integers got from the receiver.

My question is when I use the receive program, I get the decoded hexadecimal value for even the Unknown signals. And can I use this small decoded signal to send signals apart from the long list of integers. 

I am trying to send these codes from android. It would be quite easy to send and store the small hexadecimal decoded value.

Is there a way to use the decoded value to send for raw signals with some encodings at arduino?
If the signal is reported as "unknown" the library couldn't identify the protocol (RC5, RC6, NEC, SONY, etc).  If the library doesn't know the protocol,  the decoded number is meaningless. Simply put, an IR remote transmission has a frequency; a header; some data (the actual remote command); and a footer.  Without knowing the protocol the library doesn't know the length and shape of each section, so the purpose of the decoded number is only to show quickly if the decoding is receiving the same code at each keypress. You can verify this yourself.  Every time something makes an already known remote code be reported as "unknown", the code received is different from a real code, so simply guessing (or knowing beforehand) the protocol is not going to help anyway.