first divide your third column (SeqRange) in two columns with the lower
boundary in column C and the upper boundary in column D

After this use the following array formula (entered with
CTRL+sHIFT+ENTER) on your second sheet:
=MATCH('sheet1'!$B$1:$B$100,MATCH(1,(A1='sheet1'!$ A$1:$A$100)*(B2='she
et1'!$C$1:$C$100)*(B2<='sheet1'!$D$1:$D$100),0))