OFFSET
0,4
COMMENTS
Conjecture: Given any even integer E not a power of 2 (see A078426) there exists a positive integer N such that for all n>=N the equation sigma(m)=E^n has at least one solution for m.
LINKS
Max Alekseyev, Table of n, a(n) for n = 0..100
EXAMPLE
a(4)=136647=3^4*7*241 since sigma(3^4*7*241)=(11^2)(2^3)(2*11^2)=2^4*11^4 and 136647 is the smallest such number.
CROSSREFS
KEYWORD
nonn
AUTHOR
Walter Kehowski, Sep 06 2010
EXTENSIONS
Terms a(37) onward (in b-file) from Max Alekseyev, Mar 04 2014
STATUS
approved