A049010 Mean divisor of n differs by <= 1 from mean divisor of all numbers from 1 to n-1.

2, 3, 4, 6, 360, 420, 480, 504, 630, 1400, 1540, 1760, 1820, 2912, 4440, 4464, 6888, 7150, 8856, 9920, 10290, 14805, 18330, 23058, 30784, 31725, 42822, 50864, 52338, 58653, 81627, 96186, 114513, 117819, 161253, 192104, 244970, 365180, 560014, 638480, 785148

Offset

1,1

Links

Amiram Eldar, Table of n, a(n) for n = 1..90

Example

At 161253, 10920.0-10919.87+=0.127+, which is a difference of <1.

Mathematica

t = {1, 1}; seq = {}; Do[s = DivisorSigma[#, n] & /@ {0, 1}; If[Abs[s[[2]]/s[[1]] - t[[2]]/t[[1]]] <= 1, AppendTo[seq, n]]; t += s, {n, 2, 162000}]; seq (* Amiram Eldar, Sep 06 2019 *)

Crossrefs

Cf. A000005, A000203, A048978.

Sequence in context: A135236 A029962 A259388 * A340100 A361396 A021903

Adjacent sequences: A049007 A049008 A049009 * A049011 A049012 A049013

Keyword

easy,nonn

Author

Enoch Haga

Extensions

a(1) corrected and more terms added by Amiram Eldar, Sep 06 2019

Status

approved