John Selfridge - Rest in Peace

[Joe O]

In 1962, John Selfridge proved that 78,557 is a Sierpinski number; he showed that, when k=78,557, all numbers of the form k*2^n+1 have a factor in the covering set {3, 5, 7, 13, 19, 37, 73}. Five years after, he and Sierpiński proposed (but could not prove) the conjecture that 78,557 is the smallest Sierpinski number, and thus the answer to the Sierpinski problem. Seventeen or Bust is currently trying to prove this statement. At this moment 6 from the original 17 possibilities remain.

Source: RIP John Selfridge

Obituary: JOHN SELFRIDGE (1927-2010)