Sum of primes between given range
J,41 32 19 characters:
Update
(simple sieve)
g=:+/@(*1&amp;p:)@-.&amp;i.

e.g.
100 g 1
1060
250000x g 48
2623030823

Previous
h=:3 :'+/p:i.(_1 p:&gt;:y)'
f=:-&amp;h&lt;:

eg:
100 f 1
1060