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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 Jaroslav Krizek, Table of n, a(n) for n = 1..10000. 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 Cf. A024816, A054024. Sequence in context: A064380 A290732 A353201 * A229949 A126214 A126801 Adjacent sequences: A229107 A229108 A229109 * A229111 A229112 A229113 KEYWORD nonn,easy AUTHOR Jaroslav Krizek, Sep 22 2013 STATUS approved

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Last modified November 30 23:40 EST 2023. Contains 367464 sequences. (Running on oeis4.)