OFFSET
2,1
COMMENTS
If n=p^i+1 then a(n)=p^i.
Unitary sigma = A034448 = sum of divisors d with gcd(d,m/d)=1.
Note that a(27) > 10^70. - Jack Brennen, Feb 04 2014
EXAMPLE
UnitarySigma(216) = 2^2*3^2*7 = (7/6)*216.
CROSSREFS
KEYWORD
nonn
AUTHOR
Yasutoshi Kohmoto Mar 09 2009
EXTENSIONS
Corrected a(13) and added a(22) found by Jack Brennen. M. F. Hasler, Feb 04 2014
a(23)-a(26) from Jack Brennen, Feb 04 2014
STATUS
approved