ROSECODE 443
Central binomial coefficients
The binomial coefficients can be arranged in triangular form like this:
1
1 1
1 2 1
1 3 3 1
1 4 6 4 1
1 5 10 10 5 1
1 6 15 20 15 6 1
1 7 21 35 35 21 7 1
......
It is known as Pascal's triangle.
The middle coefficients of the even-numbered rows (row numbering starts from zero) form a sequence : 1, 2, 6, 20, 70, 252, 924, 3432, 12870, 48620, 184756, .... It has been proven that no number with is squarefree.
Let be divided by largest squarefree divisor of . For example, and its largest squarefree divisor is , so .
Let be the sum of all for from to . You are given , and .
Find .
1
1 1
1 2 1
1 3 3 1
1 4 6 4 1
1 5 10 10 5 1
1 6 15 20 15 6 1
1 7 21 35 35 21 7 1
......
It is known as Pascal's triangle.
The middle coefficients of the even-numbered rows (row numbering starts from zero) form a sequence
Let
Let
Find