A250399 Composite numbers whose sum of aliquot parts divides the sum of their unrelated numbers.

4, 14, 63, 85, 1649, 3127, 6401, 11521, 14121, 30005, 30629, 33101, 45671, 58829, 78227, 82947, 90581, 110975, 159877, 185399, 227341, 308179, 331918, 336299, 359413, 439619, 466759, 476677, 494321, 618701, 666409, 898967, 1044611, 1113641, 1228417, 1248707

Offset

1,1

Comments

For a definition of unrelated number see A045763.

Links

Table of n, a(n) for n=1..36.

Example

There is no unrelated number to 4. Therefore 0 / (sigma(4)-4) = 0 / (7-4) = 0 is integer.
Unrelated numbers to 14 are 4, 6, 8, 10, 12 and their sum is 40. Now, 40 / (sigma(14) - 14) = 40 / (24 - 14) = 40 / 10 = 4, that is integer.

Maple

with(numtheory); P:=proc(q) local n;
for n from 1 to q do if not isprime(n) then
if type((1+n*(n+1)/2-sigma(n)-n*phi(n)/2)/(sigma(n)-n), integer)
then print(n); fi; fi; od; end: P(10^5);

Crossrefs

Cf. A000203, A045763, A066760, A112774, A250398.

Sequence in context: A082033 A009339 A050912 * A149494 A322206 A149495

Adjacent sequences: A250396 A250397 A250398 * A250400 A250401 A250402

Keyword

nonn

Author

Paolo P. Lava, Nov 21 2014

Status

approved