OFFSET
1,2
LINKS
Giovanni Resta, Table of n, a(n) for n = 1..34 (terms < 2*10^9)
EXAMPLE
Divisors of 71951 are 1, 11, 31, 211, 341, 2321, 6541, 71951.
sigma(1) = 1, sigma(11) = 12, sigma(31) = 32, sigma(211) = 212, sigma(341) = 384, sigma(2321) = 2544, sigma(6541) = 6784, sigma(71951) = 81408.
(1^2/1 + 12^2/11 + 32^2/31 + 212^2/211 + 384^2/341 + 2544^2/2321 + 6784^2/6541 + 81408^2/71951) = 102625.
MAPLE
with(numtheory); ListA226564:=proc(q) local a, b, k, n;
for n from 1 to q do a:=[op(divisors(n))]; b:=add(sigma(a[k])^2/a[k], k=1..nops(a));
if type(b, integer) then print(n); fi; od; end: ListA226564(10^6);
CROSSREFS
KEYWORD
nonn
AUTHOR
Paolo P. Lava, Jun 11 2013
EXTENSIONS
a(12)-a(30) from Giovanni Resta, Jun 11 2013
STATUS
approved