A162826 Positive numbers n such that 2*60*n/(60+n) are integers.

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

Author

Vladimir Joseph Stephan Orlovsky, Jul 13 2009

Keywords

• nonn
• fini
• full

Crossrefs

Cf. A162688, A162689, A162690, A162691, A162692, A162693, A162694, A162817, A162818, A162819, A162820, A162821, A162822, A162823, A162824, A162825

Programs

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 *)

Extensions

Sign in definition flipped by R. J. Mathar, Jul 31 2009