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Numbers n such that 2*n - 1 < sigma(n) - sigma(n-2).
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%I #13 Nov 23 2019 02:47:45

%S 1680,2520,3360,3780,3960,4200,4680,5040,6300,6720,7560,7920,8820,

%T 9240,9360,10080,10800,10920,11340,11760,11880,12600,13440,13860,

%U 14040,15120,15840,15960,16380,16800,17280,17640,18480,18900,19800,20160,20520,21000,21420

%N Numbers n such that 2*n - 1 < sigma(n) - sigma(n-2).

%C Also numbers n such that antisigma(n) < antisigma(n-2), where antisigma(n) = A024816(n) = the sum of the non-divisors of n that are between 1 and n.

%C Sequence contains anomalous increased frequency of values ending with digit 0.

%C Conjecture: there are no numbers n such that antisigma(n) < antisigma(n-3).

%H Jaroslav Krizek, <a href="/A231548/b231548.txt">Table of n, a(n) for n = 1..228, all terms < 10^5</a>

%e 1680 is in sequence because antisigma(1680) = 1406088 < antisigma(1678) = 1406161.

%Y Cf. A024816, A213547 (numbers n such that antisigma(n) < antisigma(n-1)).

%K nonn

%O 1,1

%A _Jaroslav Krizek_, Nov 12 2013