Write an app that adds time 15 times according to specs

I need a program created where I can enter a time (say 12:30pm) and press a button and have the app calculate 15 different (time) intervals - in 1/2 hour increments - from where the time began, so I can transfer them to a schedule I have. So a formula example would look like this: time=12:30 1. +2.5 2. +5 3. +7.5 4. +10 5. +7.5 6. +5 7. +2.5 8. +5 9. +7.5 10. +10 11. +7.5 12. +5 13. +5 14. +10 15. +5 Which would convert into this: time = 12:30 1. +2.5 = 3:00 2. +5 = 8:00 3. +7.5 = 3:30am 4. +10 = 1:30 5. +7.5 = 9:00 6. +5 = 1:00am 7. +2.5 = 3:30am 8. +5 = 8:30am 9. +7.5 = 4:00 10. +10 = 2:00am 11. +7.5 = 9:30am 12. +5 = 2:30 13. +5 = 7:30 14. +10 = 5:30am 15. +5 = 10:30am Note: I need to be able to change the settings (different time intervals, etc). Also need to have this consolidated into one folder, so I could save schedules, etc. The file should be small and VERY quick - I just pop in a time and press enter. Send any questions.