OFFSET
1,2
COMMENTS
Antisigma(n) = A024816(n) = sum of numbers less than n which do not divide n.
Also numbers n such that there is some number k > 0 with property: antisigma(n) = k*(n+1). Corresponding values of numbers k: 0, 0, 6, 8, 50, 102, 230, 323, 510, 974, 1486, 9678, …
EXAMPLE
Antisigma(19359) = 187366080 = 9678*19359 + 9678.
PROG
(Magma) [n: n in [1..1000000] | u eq 0 where u is (Floor((((n*(n+1)) div 2 - SumOfDivisors(n)) div n))) - (((((n*(n+1)) div 2)-SumOfDivisors(n)) mod (n)))]
(PARI) isok(n) = my(as = n*(n+1)/2 - sigma(n)); (as\n == as % n); \\ Michel Marcus, Jun 26 2014
CROSSREFS
KEYWORD
nonn
AUTHOR
Jaroslav Krizek, Jun 25 2014
EXTENSIONS
a(16)-a(18) from Michel Marcus, Jun 26 2014
STATUS
approved