ROSECODE 379
A special subset
Let SN be the set of positive numbers less or equal to N.
SN={1,2,...,N}
Consider the subsets with the following properties:
none of the elements is a prime number none of the elements contains any prime digit(s) none of any 2 elements' difference is a prime number none of any 2 elements' difference contains any prime digit(s)
Find the subset of S100000 with the maximal sum.
Answer format: sum
Example: 20 for S10 subsets: {1}, {1,9}, {1,9,10}, {1,10}, {4}, {4,8}, {4,10}, {6}, {6,10}, {8}, {8,9}, {9}, {9,10}, {10}
[My timing: < 1m]