The
whole story began around the
turn of the millennium when Carlos Rivera
observed that 39 is a number with the
following property:
(P1) A non-prime number equal to the sum of consecutive primes from the least prime factor to the largest prime factor.
Of course, 39 = 3 * 13 = 3 +
5 + 7 + 11 + 13.
It
is not difficult to verify that 10, 155 and 371 are other
numbers with this property. Later (Jul. 2000), Jud McCranie found the 5th
number:
2935561623745 = 5 * 19 * 53 * 61 * 9557877 = 5
+ 7 + 11 + ... + 9557877.
454539357304421 = 3536123 * 128541727 =
3536123 + 3536129 + 3536131 + ... + 128541727.
So, six numbers
with the property (P1) are known up to now. One can find them in the Online
Encyclopedia of Integer Sequences under the code A055233.
We change the
property somewhat now:
(P2) A non-prime-square number equal to the
sum of squares of consecutive primes from the least prime factor to the largest prime
factor.
The smallest
number with this property is 315797.
Indeed,
315797 = 31 * 61 *
167 = 312 + 372 + 412 + ... + 1672.
Question
A: Find other numbers with the property (P2).
We can continue.
(P3) A non-prime-cube number equal to the sum
of cubes of consecutive primes from the least prime factor to the largest prime factor.
In this case, there
is a nice solution: 160.
160 = 25
* 5 = 23 + 33 + 53.
Question
B: Find other numbers with the property (P3).
And finally:
Question C: The first, second and third powers of primes can be generalized to any n-th power. Find also any numbers for n>3.
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