A244326 Numbers k such that floor(antisigma(k)/k) < floor(antisigma(k - 1)/(k - 1)).

36, 48, 60, 72, 84, 90, 96, 108, 120, 132, 144, 156, 168, 180, 192, 210, 216, 240, 252, 264, 270, 280, 288, 300, 312, 324, 330, 336, 360, 378, 384, 390, 396, 408, 420, 432, 450, 456, 468, 480, 504, 510, 528, 540, 552, 560, 570, 576, 588, 600, 612, 624, 630, 648

Offset: 1

Author

Jaroslav Krizek, Jun 25 2014

Keywords

• nonn

Comments

Antisigma(n) = A024816(n) = the sum of the non-divisors of n that are between 1 and n.

Numbers from A166069 (multiply perfect numbers k such that sigma(k)/k > 2) are members of this sequence.

Links

• Jaroslav Krizek, Table of n, a(n) for n = 1..8787 (all terms < 10000)

Crossrefs

Cf. A024816, A166069, A244324, A244325.

Programs

Magma

[k: k in [2..10000] | Floor((((k*(k+1))div 2  - SumOfDivisors(k)) div k)) lt Floor((((k*(k-1))div 2  - SumOfDivisors(k-1)) div (k-1)))];

Mathematica

With[{as=Table[Floor[Total[Complement[Range[2,n],Divisors[n]]/n]],{n,1000}]},Flatten[Position[Partition[as,2,1],?(First[#]>Last[#]&),{1},Heads->False]]]+1 (* _Harvey P. Dale, Sep 10 2014 *)