OFFSET
1,1
COMMENTS
The ratio is required to be > 1.
For a(5), (1 + r + r^2 + r^3 + r^4) + r is composite. hence the first term of the geometric progression is >1. For a(5) a = 5 and r = 2. This is true For all odd n.
EXAMPLE
a(3) = (3+6+12) + 2 = 23.
a(4) = (1+2+4+8 ) + 2 = 17.
a(6) = (3+6+12+24+48+96) + 2= 191.
CROSSREFS
KEYWORD
easy,nonn
AUTHOR
Amarnath Murthy, Sep 25 2003
EXTENSIONS
More terms from David Wasserman, Jul 25 2005
STATUS
approved