OFFSET
1,2
EXAMPLE
a(4) = 169 = 13^2 has a prime signature of 4 = 2^2 and 169 == 1 (mod 7 = a(3)).
CROSSREFS
KEYWORD
nonn
AUTHOR
Amarnath Murthy, Jan 05 2006
EXTENSIONS
Corrected and extended by Joshua Zucker, May 07 2006
STATUS
approved