Irrational Numbers from Adjacent Natural Numbers (Part VIIIa)

A Staircase Sequence of Irrational Numbers Derived from (n((xy) + x + y)

This is a continuation of the induction proofs Part VIIa and Part VIIb for n((xy) + x + y).

It has been shown (Between_two_Rational_Numbers on Wiki) that between two real numbers (ℝ) there exists an irrational number. Accordingly, it will be shown here that between two adjacent natural numbers (ℕ) there exists an irrational number (ℝ\ℚ). In addition, an arithmetic progression or sequence of irrational numbers will be generated in this section where there are two common differences (Δ1) and (Δ2) between the irrational numbers generated from Part VIIb for n((xy) + x + y). So, therefore, let's proceed as follows:

The sequence derived from the equation n((xy) + x + y) is shown in Tables I and II where the values of n range from 1 to 14, while those of x and y range, respectively, from 1 to 28 and 2 to 29. The differences (Δ1) and (Δ2) between the irrational numbers are, respectively, about 0.5 and 1.5 where Δ2 corresponds to the end of one Δ1 to the start of the next Δ1 in the sequence, and approach these values as x and y increase without bound. The value for each n((xy) + x + y), is calculated to 6 decimal places, is irrational and each of these values indeed falls between their respective consecutive natural numbers. In addition, the fourth column heading is SQRT = n((xy) + x + y).

Table I Irrational (Sequence)
nx y SQRTΔ1/Δ2
1121.870829
1232.3804760.509647
2343.9370041.556278
2454.4271890.490185
3565.9581881.530999
3676.4475910.489403
4787.9686891.521098
4898.4590520.490363
59109.9749691.515917
5101110.4663960.491428
6111211.9791491.512752
6121312.4715060.492357
7131413.9821321.510625
7141514.4752660.493135
Table II Irrational (Sequence)
nx y SQRTΔ1/Δ2
8151615.9843671.509101
8161716.4781500.493782
9171817.9861061.507956
9181918.4804310.494325
10192019.9874961.507066
10202120.4822800.494784
11212221.9886331.506353
11222322.4838110.495177
12232423.9895811.505771
12242524.4850980.495516
13252625.9903831.505285
13262726.4861950.495812
14272827.9910701.504875
14282928.4871420.496072

If the natural numbers are plotted on a grid vs n the following picture of a staircase is obtained. The blue lines are the Δ1 differences of 0.5 within the run of the staircase, while the black diagonal, is the difference Δ2 of 1.5; the red, in addition, is a jump from one level to the next (the rise of the staircase).

Picture of a staircase

Is still possible to write out the as one line sequence (for the first ten natural numbers, in red):

1, 1.870829, 2, 2.380476, 3, 3.937004, 4, 4.427189, 5, 5.958188, 6, 6.447591, 7, 7.968689, 8, 8.459052, 9, 9.974969, 10, 10.466396

However, while when we look at the sequence in this way (as a ramp), there's no way of knowing if the sequence is a staircase or a ramp like the sequence derived from xy in Part I which has no n levels. The Δ1 and Δ2 can still be read off as well as the differences between a natural number and the Δ1 to its right which approaches 0.25 and 0.75 for a pair of natural numbers. In the staircase sequence the n is required in order that the irrational numbers fall between their two adjacent natural numbers. It wasn't expected that the irrational numbers fell right smack-dab in the same general areas as shown in the figure. In addition, connecting all the 0.25 terms together and all the 0.75 terms together gives "rise" to two parallel ramps where the sequence may have both ramp and staircase properties depending on the view.

Go back to Part VIIa and Part VIIb for proof by induction for and Part VIIb for n((xy) + x + y).

Go to Part I or Part IV for non-staircase methods. Go back to homepage.


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