Let E=[13+150]+[13+250]+…+ up to 50 terms, then
E is divisible by exactly 2 primes
E is prime
E≥30
E≤35
For, 1≤x≤33,13<13+x50<1 therefore,
[13+x50]=0for1≤x≤33
For 34≤x≤50,1<13+x50<43
⇒[13+x50]=1 for 34≤x≤50
Thus E=17