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For example, successively searching through the positive integers (1, 2, 3, ...) to see if we can find an odd perfect number is quite easy to write and is a partially correct program that would find an odd perfect number, if such a number exists (see box). However, to say this program is totally correct (i.e., that it will find such a number and terminate) would be to assert that an odd perfect number actually exists, which is currently not known

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