Given set is
S=1,2,3,5,7,10,11
Elements of the type 3k is 3.
Elements of the type 3k+1 are 1,7,9.
Elements of the type 3k+2 are 2,5,11
Subset containing one element S1=1
Subsets containing two elements S2
=C13×C13=9
Subsets containing three elements S3
=C13×C13+1+1=11
Subsets containing four elements S4
=C33+C33+C23×C23=11
Subsets containing five elements S5
=C23×C23×1=9
Subsets containing six elements S6=1
Subsets containing seven elements S7=1
Required number
=1+9+11+11+9+1+1
=43