@quasi : deny "ab + cd"

dear quasi

i was thinking about the set ab + cd with all variables integers >=2.

or in other words ; the set of positive integers that are the sum of 2 (positive) composites.

7 for example does not belong to it.

although ab + cd seems simple and is a polynomial of first degree, it does not appear so simple to me.

we know that deny [ab] = prime and cannot be written in polynomial without conditions like > 0.

but what is deny[ab + cd] ?

related to primes ?

suppose we allow polynomials of integer and primevalued variables ; then can deny be stated in such a polynomial variant ?

can deny [ab + cd] be expressed in closed form perhaps ?

regards
tommy1729
.

Relevant Pages

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