CBRNG using Reikna package in python to regenerate random numbers

I am trying to use reikna package in python to generate counter based random numbers. Actually, i have to generate the same random number for a seed. So, I have a seed tuple (a,b,c) (a,b and c are integers). I want to write the function rand123((a,b,c)) so that I will get a random number and I have to get the same random value whenever I use the seed (a,b,c).

Using the library random is very expensive if I give the seed as (a,b,c) and find the random number. In c++/c cbrng is very fast.

Please help me in writing the function.

Thanks, jai.