OFFSET
1,1
COMMENTS
This is to categorize prime signatures such that p^a*q^b*r^c ... +1 is composite, p,q,r are arbitrarily chosen primes. Example: Perfect odd powers + 1 is always composite. Are there other examples? Exceptions like 3 and 5 are to be ignored.
EXAMPLE
8 = 2^3 is a member as 8 has a prime signature p^3 and all numbers of the form p^3+1 are composite.
9 is also a member though 2^2+1 = 5 is a prime but for all odd primes p^2+1 is even.
216 = 2^3*3^3 is a member because p^3*q^3+1 is always divisible by pq+1.
CROSSREFS
KEYWORD
nonn
AUTHOR
Amarnath Murthy, Apr 01 2004
EXTENSIONS
More terms from David Wasserman, Sep 12 2006
STATUS
approved