OFFSET
1,2
COMMENTS
Antisigma(n) = A024816(n) = sum of numbers less than n which do not divide n.
Union of A065091 (odd primes) and sequence nonprimes 1, 4, 36, ... (all terms < 10^5).
No more composite terms to 10^10. - Charles R Greathouse IV, Nov 02 2014
LINKS
Jaroslav Krizek, Table of n, a(n) for n = 1..5000.
EXAMPLE
antisigma(36) mod 36 => 575 mod 36 = 35.
PROG
(Magma) [n: n in [1..1000] | n-1 eq ((n*(n+1) div 2-SumOfDivisors(n)) mod n)]; // Jaroslav Krizek, May 28 2014
(PARI) is(n)=(n*(n+1)/2-sigma(n)+1)%n==0 \\ Charles R Greathouse IV, Nov 02 2014
CROSSREFS
KEYWORD
nonn
AUTHOR
Jaroslav Krizek, Sep 26 2013
STATUS
approved