OFFSET
3,2
EXAMPLE
3*2*3*4*5*6*7/(2*3*5*7) -1 = 71 prime twin of 73
3*2*3*4*5*6*7/(2*3*5*7) +1 = 73 prime twin of 71, so k(4)=3 as p(4)=7
CROSSREFS
KEYWORD
nonn
AUTHOR
Pierre CAMI, Nov 25 2006
STATUS
approved