A sequence with \(N\) elements will be called a permutation of the \(N\) smallest
natural numbers if it contains all natural numbers from \(1\) to \(N\).
It is known that the sequence \(\left\{ a_{i} \right\}\) is a permutation of the
\(n\) smallest natural numbers (\(n>3\)).
The elements of the sequence \(\left\{ b_{i} \right\}\) (\(1 \leq i \leq n-1\))
are computed by the formula \(b_{i}=\left|a_{i+1}-a_{i}\right|\).
The elements of the sequence \(\left\{ c_{i} \right\}\) (\(1 \leq i \leq n-2\))
are computed by the formula \(c_{i}=\left|b_{i+1}-b_{i}\right|\).
Prove that \(\left\{ b_{i} \right\}\) and \(\left\{ c_{i} \right\}\) cannot both
simultaneously be permutations of the \(n-1\) and \(n-2\) smallest natural numbers,
respectively!
Skaitļu virkni, kurā ir \(N\) elementi, sauksim par \(N\) mazāko
naturālo skaitļu permutāciju, ja tajā atrodami visi
naturālie skaitļi no \(1\) līdz \(N\).
Zināms, ka virkne \(\left\{ a_{i} \right\}\) ir \(n\) (\(n>3\)) mazāko naturālo
skaitļu permutācija.
Virknes \(\left\{ b_{i} \right\}\) (\(1 \leq i \leq n-1\)) elementus aprēķina
pēc formulas \(b_{i}=\left|a_{i+1}-a_{i}\right|\).
Virknes \(\left\{ c_{i} \right\}\) (\(1 \leq i \leq n-2\)) elementus aprēķina
pēc formulas \(c_{i}=\left|b_{i+1}-b_{i}\right|\).
Pierādīt, ka \(\left\{ b_{i} \right\}\) un \(\left\{ c_{i} \right\}\)
vienlaikus abas nevar būt attiecīgi \(n-1\) un \(n-2\) mazāko
naturālo skaitļu permutācijas!