Develop a Mac Application

I am looking for a very basic brain memory training application which should work like this: Please view the attached image for the basic idea behind the application then read what I have written here for more detail. The interface just needs to be a keypad with digits 1 to 8 at the bottom of the screen (preferably arranged in rows of 3 like a phone keypad). In the top half of the screen is where the numbers that need to be remembered will need to flash up briefly one by one. The numbers need to be random, be single digits between 1 and 8 and flash briefly on the screen (one at a time) for about 0.25 seconds with a 0.50 second gap between them. After the first 3 numbers have flashed on the screen, the user then must input the number which was displayed 2 numbers prior (as is shown in the attached example). When the number has been pressed, after the 0.5 second delay another number will be displayed for 0.25 seconds and the user will once again need to press the number which has been displayed 2 numbers prior. New numbers should only be displayed when the user has selected an entry on the keypad (they have as long as they need to make a selection but will get a lower score the longer they take as they will have less opportunities in the 60 seconds if they take more time to make each selection). The user shouldn’t get any indication on whether the answers are correct until the end of 60 seconds is up when the total number of correct/incorrect numbers is displayed. If it is easy enough to program, it would also be good if a few timers can be selected. Maybe 60 seconds, 120 seconds & 180 seconds. If this requires too much extra effort, 60 seconds only will be fine. I am happy for this to be either an Apple Mac OSX application or Android application (whichever takes less time to create). Thank you.