A162817 Positive numbers n such that 40*n/(40+n) are integers.

10, 24, 40, 60, 120, 160, 280, 360, 760, 1560

Offset: 1

Author

Vladimir Joseph Stephan Orlovsky, Jul 13 2009

Keywords

• nonn
• fini
• full

Crossrefs

Cf. A162688, A162689, A162690, A162691, A162692, A162693, A162694

Cf. A127730. [From Franklin T. Adams-Watters, Aug 07 2009]

Programs

Mathematica

f[a_,b_]:=(a*b)/(a+b); a=40;lst={};Do[If[f[a,n]==IntegerPart[f[a,n]], AppendTo[lst,n]],{n,9!}];lst
Select[Range[1600],IntegerQ[(40#)/(40+#)]&] (* Harvey P. Dale, Oct 11 2011 *)

Extensions

Keywords fini,full added by R. J. Mathar, Jul 31 2009