Sigma of P(n) |

Let's define a function over the non-negative integers in the following manner:Note: this problem was shared to WTM by Reza Kassai, of Shiraz, Iran.

- P(n) = n when
nis a one-digit integer.

- P(n) = the product of all the digits of
nwhenn> 9.Example: P(1729) = 126, because 1 × 7 × 2 × 9 = 126.

Evaluate the following:

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