Problem # 20 : Key numbers

Any sequence of strictly positive integers can be expressed as a single key number using the following technique :-

Example : 4 5 2 1 can be expressed as 2⁴  x 3⁵ x 5² x 7¹ = 680400
i.e the n-numbers are the exponents of the first n-prime numbers.

Write a sub-routine KEYNO(A) which applies prime factorization to the key number A to give the sequence.

You can assume that the number is a product of successive primes.
(i.e it cannot be 2² x 7¹, it must be successive primes)

Sample Output
KEYNO(60) will return 2 1 1    (as 60 = 2² x 3¹ x 5¹)
KEYNO(72) will return 3 2   (as 72 = 2³ x 3²)

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