login
A250398
Composite numbers whose sum of divisors divides the sum of their unrelated numbers.
2
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
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
KEYWORD
nonn
AUTHOR
Paolo P. Lava, Nov 21 2014
STATUS
approved