1,1

Rewrite 100n^2/(100+n^2) as an I : n=sqrt(100I/(100-I)), where a finite substitution for I results.

Instead of 100, we could use 72 and get n=8,24,48,64; we could use 162 and get n=54,108,144,150. Many other values are possible.

Table of n, a(n) for n=1..5.

for n=20, 100*20^2/(100+20^2)=I or 80.

Select[Range[1000], IntegerQ[100*#^2/(100 + #^2)] &] (* T. D. Noe, Jan 29 2014 *)

Cf. A162688.

Sequence in context: A065969 A306775 A027884 * A026357 A117518 A107486

Adjacent sequences: A236388 A236389 A236390 * A236392 A236393 A236394

nonn,fini,full

Larry J Zimmermann, Jan 24 2014

approved