

A229114


Numbers k such that antisigma(k) mod k = antisigma(k+1) mod (k+1).


0



1, 8, 27, 3115, 3451, 4725, 10611, 15951, 20155, 27643, 74875, 2767675, 18390564, 27923284, 50293331, 425018875, 897002491, 10561657872, 15193530235, 20939306635, 40882585915, 80585844499
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OFFSET

1,2


COMMENTS

Antisigma(k) = A024816(k) = sum of numbers less than k which do not divide k.
For k < 10^8, 2 is the only number such that sigma(k) mod k = sigma(k+1) mod (k+1).


LINKS



EXAMPLE

a(3) = 27 because antisigma(27) mod 27 = 338 mod 27 = antisigma(28) mod 28 = 350 mod 28 = 14.


PROG

(PARI) s=1; r=0; for(n=1, 10^9, n1=n+1; s=s+n1; r1=(ssigma(n1))%n1; if(r==r1, print(n)); r=r1) /* Donovan Johnson, Sep 27 2013 */


CROSSREFS



KEYWORD

nonn,more


AUTHOR



EXTENSIONS



STATUS

approved



