hashing a small number to a random looking 64 bit integer

Question

I am looking for a hash-function which operates on a small integer (say in the range 0...1000) and outputs a 64 bit int.

The result-set should look like a random dis

Answer 1

1,000 * 1,000 = 1,000,000. That fits well within an Int32.

Subtract the low bound of your range, from the number. Square it, and use it as a direct subscript into some sort of bitmap.