MathDB

Find the number of four-element subsets of

\{1,2,3,4,\dots, 20\}

with the property that two distinct elements of a subset have a sum of

16

, and two distinct elements of a subset have a sum of

24

. For example,

\{3,5,13,19\}

and

\{6,10,20,18\}

are two such subsets.

Problem Statement