Problem 57507. Easy Sequences 88: Double Summation of a Combinatorial Function

Given two positive integers a and b, , we define the function as the sum of the reciprocals of the products of all combinations of 1 to a taken b at a time. In Matlab we say that: R = sum(1./prod(nchoosek(a,b)')). For example if and :
>> R = sum(1./prod(nchoosek(1:5,3)'))
R =
0.7083
Given a positive integer x, we are asked to evaluate the following double summation:
For example for :
In which, in Matlab, evaluates to:
>> S = sum(arrayfun(@(i) sum(1./prod(nchoosek(1:3,i)')),2:2))+sum(arrayfun(@(i) sum(1./prod(nchoosek(1:4,i)')),2:3))+sum(arrayfun(@(i) sum(1./prod(nchoosek(1:5,i)')),2:4))
S =
5.5833
Please round-off S to the nearest whole number. Therefore, the final output for the above example is .

Solution Stats

100.0% Correct | 0.0% Incorrect
Last Solution submitted on Jan 10, 2023

Problem Comments

Solution Comments

Show comments

Problem Recent Solvers1

Suggested Problems

More from this Author116

Community Treasure Hunt

Find the treasures in MATLAB Central and discover how the community can help you!

Start Hunting!