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A162828
Positive numbers n such that 2*90*n/(90+n) are integers.
1
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
1,1
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 *)
KEYWORD
nonn,fini,full
AUTHOR
EXTENSIONS
Sign in definition flipped by R. J. Mathar, Jul 31 2009
STATUS
approved