Since,H.C.F. of (91,n)>1.
Hence, n should be multiple of 7 or 13 or both.
Hence, when n is multiple of 7,
Number of terms=14, t1=105, l=196
∴S1=214(105+196)=7×301=2107
When n is multiple of 13,
Number of terms =8,t1=104,l=195
∴S2=28×299=1196
When n is multiple of 91
∴ Number of term =1
S3=182
∴ Required sum =2107+1196−182=3121