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A231548
Numbers n such that 2*n - 1 < sigma(n) - sigma(n-2).
3
1680, 2520, 3360, 3780, 3960, 4200, 4680, 5040, 6300, 6720, 7560, 7920, 8820, 9240, 9360, 10080, 10800, 10920, 11340, 11760, 11880, 12600, 13440, 13860, 14040, 15120, 15840, 15960, 16380, 16800, 17280, 17640, 18480, 18900, 19800, 20160, 20520, 21000, 21420
OFFSET
1,1
COMMENTS
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.
Sequence contains anomalous increased frequency of values ending with digit 0.
Conjecture: there are no numbers n such that antisigma(n) < antisigma(n-3).
EXAMPLE
1680 is in sequence because antisigma(1680) = 1406088 < antisigma(1678) = 1406161.
CROSSREFS
Cf. A024816, A213547 (numbers n such that antisigma(n) < antisigma(n-1)).
Sequence in context: A258920 A268288 A175749 * A179693 A290704 A342876
KEYWORD
nonn
AUTHOR
Jaroslav Krizek, Nov 12 2013
STATUS
approved