OFFSET
1,1
EXAMPLE
If n = 11746, starting from the least significant digit, let us cut the number into the set 6, 46, 746, 1746. We have:
sigma(6) = 12;
sigma(46) = 72;
sigma(746) = 1122;
sigma(1746) = 3822
and 12 + 72 + 1122 + 3822 = 5028 = phi(11746).
MAPLE
with(numtheory); P:=proc(q) local a, k, n;
for n from 2 to q do a:=0; k:=1; while (n mod 10^k)<n do
a:=a+sigma(n mod 10^k); k:=k+1; od;
if phi(n)=a then print(n); fi; od; end: P(10^9);
CROSSREFS
KEYWORD
nonn,base
AUTHOR
Paolo P. Lava, Apr 14 2014
EXTENSIONS
a(14)-a(30) from Giovanni Resta, Apr 16 2014
STATUS
approved