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

Author

Paolo P. Lava, Nov 21 2014

Keywords

• nonn

Comments

For a definition of unrelated number see A045763.

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

Examples

			There is no unrelated number to 4. Therefore 0 / sigma(4) = 0 / 7 = 0 is an integer.
Unrelated numbers to 10 are 4, 6, 8 and their sum is 18. Now, 18 / sigma(10) = 18 / 18 = 1, that is an integer.
		

Links

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

Crossrefs

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

Programs

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);