Discovered with Prime95, version 25, checked by strong (Miller-Rabin) tests in all 20 prime bases from 2 to 71 with pfgw SCRIPT file, development version 20050213. Candidates were sieved to 6.7e13 with Sr2sieve.
This discovery eliminates a sequence 2^n+k from the dual Sierpinski problem search, with 3 sequences now remaining. The distributed effort "Five or Bust" is being coordinated at www.mersenneforum.org.

To be completed...