A213239 Numbers n such that sum of digits of n = sum of digits of anti-divisors of n.

5, 8, 64, 691, 1779, 2851, 6361, 9066, 9606, 9771, 10789, 10996, 18996, 21481, 22569, 27529, 27691, 31516, 36709, 36776, 42649, 48651, 53296, 56586, 58749, 60369, 64794, 72889, 76754, 78766, 79374, 79896, 80989, 86596, 90606, 90879, 92766, 96171, 98979, 108529

Offset

1,1

Links

Table of n, a(n) for n=1..40.

Example

Sum of digits of 1779 is 1+7+7+9=24.
Anti-divisors of 1779 are 2, 6, 1186 and their digits’ sum is 2+6+1+1+8+6=24.

Maple

with(numtheory);
A213239:=proc(q)
local a, b, c, d, k, n;
for n from 1 to q do
  a:=0; b:=0;
  for k from 2 to n-1 do
    if abs((n mod k)-k/2)<1 then
       c:=k; while c>0 do b:=b+(c mod 10); c:=trunc(c/10); od; fi; od;
  c:=n; d:=0; while c>0 do d:=d+(c mod 10); c:=trunc(c/10); od;
  if b=d then print(n); fi; od; end:
A213239(100000);

Prog

(Python)
[n for n in range(1, 10**5) if sum([sum([int(x) for x in str(d)]) for d in range(2, n) if n % d and 2*n % d in [d-1, 0, 1]]) == sum([int(x) for x in str(n)])] # Chai Wah Wu, Aug 08 2014

Crossrefs

Cf. A006753, A066417, A213240.

Sequence in context: A342195 A132050 A250067 * A123819 A286076 A302651

Adjacent sequences: A213236 A213237 A213238 * A213240 A213241 A213242

Keyword

nonn,base

Author

Paolo P. Lava, Jun 07 2012

Status

approved