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A162826
Positive numbers n such that 2*60*n/(60+n) are integers.
2
12, 15, 20, 30, 36, 40, 60, 84, 90, 100, 120, 140, 165, 180, 228, 240, 300, 340, 390, 420, 540, 660, 740, 840, 1140, 1380, 1740, 2340, 3540, 7140
OFFSET
1,1
MATHEMATICA
f[a_, b_]:=(a*b)/(a+b)*2; a=60; lst={}; Do[If[f[a, n]==IntegerPart[f[a, n]], AppendTo[lst, n]], {n, 9!}]; lst
Select[Range[8000], IntegerQ[(120#)/(60+#)]&] (* Harvey P. Dale, Mar 19 2019 *)
KEYWORD
nonn,fini,full
AUTHOR
EXTENSIONS
Sign in definition flipped by R. J. Mathar, Jul 31 2009
STATUS
approved