A162828 Positive numbers n such that 2*90*n/(90+n) are integers.
10, 18, 30, 45, 60, 72, 90, 110, 126, 135, 180, 210, 234, 270, 315, 360, 450, 510, 558, 585, 720, 810, 990, 1260, 1530, 1710, 1935, 2610, 3150, 3960, 5310, 8010, 16110
Offset: 1
Crossrefs
Programs
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Mathematica
f[a_,b_]:=(a*b)/(a+b)*2; a=90;lst={};Do[If[f[a,n]==IntegerPart[f[a,n]], AppendTo[lst,n]],{n,9!}];lst Select[Range[17000],IntegerQ[180 #/(#+90)]&] (* Harvey P. Dale, Sep 22 2011 *)
Extensions
Sign in definition flipped by R. J. Mathar, Jul 31 2009