A250398 Composite numbers whose sum of divisors divides the sum of their unrelated numbers.

4, 10, 22, 34, 46, 58, 82, 94, 106, 118, 142, 166, 178, 202, 214, 226, 262, 274, 298, 334, 346, 358, 382, 394, 454, 466, 478, 493, 502, 514, 526, 538, 562, 586, 622, 634, 694, 706, 718, 766, 778, 802, 838, 862, 886, 898, 922, 934, 958, 982, 1006, 1018, 1042, 1114

Offset

1,1

Comments

For a definition of unrelated number see A045763.

Most of the terms belong to A112774. First difference is at a(28) = 493.

Links

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

Example

There is no unrelated number to 4. Therefore 0 / sigma(4) = 0 / 7 = 0 is integer.
Unrelated numbers to 10 are 4, 6, 8 and their sum is 18. Now, 18 / sigma(10) = 18 / 18 = 1, 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), integer)
then print(n); fi; fi; od; end: P(10^5);

Crossrefs

Cf. A000203, A045763, A066760, A112774, A250399.

Sequence in context: A338910 A217514 A235142 * A112774 A352296 A369385

Adjacent sequences: A250395 A250396 A250397 * A250399 A250400 A250401

Keyword

nonn

Author

Paolo P. Lava, Nov 21 2014

Status

approved