Sum of Consecutive Integers
Let n be an integer greater than 1, show that 2n is the sum of two consecutive odd integers. Furthermore, show that 3n is the sum of three consecutive integers.
- 4 August, 2012 -
- Article, Math Problems -
- Tags : 104 problems, number theory, titu
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These can all be easily proven via construction.
1. There exists two consecutive odd integers whose sum is 
If there exists two odd consecutive odd integers satisfying the above property, then it must be the case that such that
(1)
Since , then
and
are consecutive integers whose sum
satisfies the above properties.
2. There exists three consecutive integers whose sum is 
Suppose there exists three consecutive integers whose sum is
, then because
is necessarily odd, it must be the case that
must also be odd as well. Since the sum of an even number and an odd number is still odd,
must be even.
(2)
Hence, the sum of is
In fact, you can easily show that
and that
etc. Hence, using similar constructions, one can show that given an expression of the form : if
is odd, then there exists
consecutive integers whose sum is
; on the other hand, if
is even, then there exists
consecutive odd integers whose sum is
.