According to my hypothesis, any natural number,
so any positive integer can be produced as the sum of the square of an integer
and a prime or at most two prime.
In this case, it
is important (otherwise the conjecture is not true) to include 1 as prime
number. (My personal point of view is that 1 should be considered as prime, but
keeping the necessary distinctions as appropriate: primes bigger than 1 or
bigger than 2. Out of respect for the tradition, it is reasonable to call prime
numbers the primes bigger than 1, big primes the primes bigger than 2, in the
end absolute prime numbers the set of all primes and the 1. 1 merit the
respect, not only because that it is the ancestor of all numbers, but because
it fulfills perfectly the most natural definition of a prime number: p is prime
number, if from a × b = p follows that a = 1 and b = p , or the opposite.)
Let us see some
examples that obviously only confirm but do not prove the conjecture.
1 = 1 + 02
2 = 1 + 12
3 = 3 + 02
4 = 3 + 12
5 = 5 + 02
6 = 5 + 12
7 = 7 + 02
8 = 7 + 12
9 = 5 + 22
10 = 1 + 32
100 = 19 + 92
1000 = 919 + 92
10000 = 199 + 992
123 = 2 + 112
1234 = 1009 + 152
12345 = 1109 + 1062
It is easy to spot
that in some cases the number can be produced in different ways. For example:
12345 = 1109 + 1062 = 2741 + 982
Interestingly,
most natural numbers can be produced as the sum of a square and one prime
number, but there are “hard” cases that can only be solved with two prime
numbers.
So far, according
to calculations – partly reported by others – from 1 to 100 there are six
exceptions.
25 = 5 + 19 + 12
34 = 11+ 23 + 02
58 = 3 + 53 + 12
64 = 11 + 53 + 02
85 = 31 + 53 + 12
91 = 2 + 89 + 02
The
"difficult" cases between 100 and 1000: 121, 130, 169, 196, 214, 289,
324, 370, 400, 526, 529, 625, 676, 706, 771, 784, 841. It can be seen that
their Frequency decreases fastly, but it is unlikely they will "run
out". I suppose for example that the numbers of the form
22(2k+1)
are all difficult cases. (It would certainly be
fitting to give a name to both types of natural numbers.)Was already made this
hypothesis, I do not know. Among other things, that is why I did not want to
give him a name (which is not important, but practical to mention it).
Moreover, I am
convinced that this statement – unfortunately – cannot be proved in the same
way as the famous Goldbach's conjecture (which, I think, has nothing to do with
Gödel's "incompleteness" theorem, but is due to the mystery of the
prime numbers).
This is our world.
March 3, 2019, Todor Simeonov
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