OFFSET
1,1
LINKS
Charles R Greathouse IV, Table of n, a(n) for n = 1..10000
FORMULA
Composite solutions to A009530(x)=2x which are not twice a prime.
EXAMPLE
n=63: d(n) = tau(n) = 6, lcm(63,6) = 126 = 2n.
PROG
(PARI) is(n)=!isprime(if(n%2, n, n/2)) && lcm(n, numdiv(n))==2*n \\ Charles R Greathouse IV, Oct 28 2013
CROSSREFS
KEYWORD
nonn
AUTHOR
Labos Elemer, Nov 18 2002
STATUS
approved