A192284 Numbers n such that the average of the anti-divisors of n is an integer.

3, 4, 6, 8, 9, 11, 15, 16, 18, 19, 20, 26, 29, 30, 34, 36, 37, 38, 47, 49, 51, 63, 64, 68, 69, 82, 93, 94, 95, 96, 106, 117, 120, 121, 131, 134, 135, 141, 155, 169, 174, 186, 187, 190, 191, 197, 200, 203, 206, 224, 226, 244, 252, 257, 271, 272, 274, 276, 289

Offset: 1

Author

Paolo P. Lava, Jul 20 2011

Keywords

• nonn

Comments

Like A003601 but using anti-divisors.

Examples

			Anti-divisors of 38 are 7: 3, 4, 5, 7, 11, 15, 25. Their sum is 70 and 70/7=10 that is an integer.
		

Links

• Paolo P. Lava, Table of n, a(n) for n = 1..1000

Crossrefs

Cf. A003601, A066272.

Programs

Maple

with(numtheory);
P:=proc(n)
local a,b,i,k;
for i from 3 to n do
  a:=0; b:=0;
  for k from 2 to i-1 do
    if abs((i mod k)- k/2) < 1 then a:=a+k; b:=b+1; fi;
  od;
  if trunc(a/b)=a/b then print(i); fi;
od;
end:
P(1000);