A160320 Numbers n for which sigma(n)/n = k+1/3 with integer k.

3, 12, 234, 1080, 6048, 6552, 435708, 4713984, 18506880, 36197280, 275890944, 299980800, 4138364160, 13286744064, 17827568640, 30600708096, 459010621440, 2198278051200, 2567400675840, 3321402084000, 4959751305600, 295185198672000, 1217745604232064

Offset

1,1

Links

Table of n, a(n) for n=1..23.

Example

a(1)=3 since sigma(3)/3=(1+3)/3=1+1/3.
a(2)=12 since sigma(12)/12=(1+2+3+4+6+12)/12=28/12=7/3=2+1/3.

Prog

(PARI) is(n)=denominator(sigma(n, -1)-1/3)==1 \\ Charles R Greathouse IV, Mar 09 2014

Crossrefs

Cf. A160321 (sigma(n)/n=k+2/3), A159907 (sigma(n)/n=k+1/2).

Sequence in context: A211892 A063801 A366504 * A321603 A297564 A280086

Adjacent sequences: A160317 A160318 A160319 * A160321 A160322 A160323

Keyword

nonn

Author

J.C. Klein (hklein(AT)planet.nl), May 08 2009

Extensions

a(11)-a(16) from Donovan Johnson, May 26 2009

a(17)-a(23) from Michel Marcus, Sep 21 2012

Status

approved