MathDB
How many ways???

Source: Cono sur Olympiad 1997 P1

November 14, 2017
combinatoricsalgebra

Problem Statement

We have 9898 cards, in each one we will write one of the numbers: 1,2,3,4,....,97,981, 2, 3, 4,...., 97, 98. We can order the 9898 cards, in a sequence such that two consecutive numbers XX and YY and the number Xāˆ’YX - Y is greater than 4848, determine how and how many ways we can make this sequence!!