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A229110 Sum of non-divisors of n reduced modulo n. 21
0, 0, 2, 3, 4, 3, 6, 5, 5, 7, 10, 2, 12, 11, 6, 9, 16, 6, 18, 8, 10, 19, 22, 0, 19, 23, 14, 14, 28, 3, 30, 17, 18, 31, 22, 35, 36, 35, 22, 10, 40, 9, 42, 26, 12, 43, 46, 44, 41, 32, 30, 32, 52, 15, 38, 20, 34, 55, 58, 42, 60, 59, 22, 33, 46, 21, 66, 44, 42 (list; graph; refs; listen; history; text; internal format)
OFFSET
1,3
COMMENTS
Numbers n such that a(n)=0 are: 1, 2, 24, 4320, 4680, ... (see A159907, conjecture by Jaroslav Krizek and further comments). - Michel Marcus, Sep 23 2013
Numbers n such that a(n)=n/2 are: 6, 28, 120, 496, 672, ... = A007691 \ {1}. - Michel Marcus, Sep 25 2013
LINKS
FORMULA
a(n) = A024816(n) mod n.
PROG
(Haskell) a229110 n = mod (a024816 n) n
(PARI) a(n) = lift(sum(i=1, n, if (n % i, Mod(i, n), 0))); \\ Michel Marcus, Sep 23 2013
(PARI) a(n)=(n*(n+1)/2-sigma(n))%n \\ Charles R Greathouse IV, Sep 23 2013
CROSSREFS
Sequence in context: A064380 A290732 A353201 * A229949 A126214 A126801
KEYWORD
nonn,easy
AUTHOR
Jaroslav Krizek, Sep 22 2013
STATUS
approved

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Last modified March 29 05:43 EDT 2024. Contains 371264 sequences. (Running on oeis4.)