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 *)
CROSSREFS
KEYWORD
nonn,fini,full
AUTHOR
Vladimir Joseph Stephan Orlovsky, Jul 13 2009
EXTENSIONS
Sign in definition flipped by R. J. Mathar, Jul 31 2009
STATUS
approved