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A227231 Numbers n such that antisigma(n) mod n = n - 1. 1
1, 3, 4, 5, 7, 11, 13, 17, 19, 23, 29, 31, 36, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 101, 103, 107, 109, 113, 127, 131, 137, 139, 149, 151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229, 233, 239, 241, 251, 257, 263 (list; graph; refs; listen; history; text; internal format)
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

Cf. A024816 (antisigma(n)), A229110 (antisigma(n) mod n).

Sequence in context: A046642 A140826 A081735 * A107036 A001605 A216570

Adjacent sequences:  A227228 A227229 A227230 * A227232 A227233 A227234

KEYWORD

nonn

AUTHOR

Jaroslav Krizek, Sep 26 2013

STATUS

approved

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Last modified March 21 07:23 EDT 2019. Contains 321367 sequences. (Running on oeis4.)