A070209 Numbers n such that [A070080(n), A070081(n), A070082(n)] is an integer triangle with integer inradius.

17, 116, 212, 269, 368, 370, 493, 561, 587, 659, 850, 1204, 1297, 1582, 1599, 1629, 1920, 1988, 2115, 2352, 2555, 2574, 2774, 2778, 3251, 3473, 3746, 3751, 4286, 4298, 4307, 4313, 4319, 4330, 4370, 4406, 5008, 5251

Offset

1,1

References

Mohammad K. Azarian, Circumradius and Inradius, Problem S125, Math Horizons, Vol. 15, Issue 4, April 2008, p. 32. Solution published in Vol. 16, Issue 2, November 2008, p. 32.

Links

Table of n, a(n) for n=1..38.

Eric Weisstein's World of Mathematics, Incircle.

R. Zumkeller, Integer-sided triangles

Example

a(3)=212: [A070080(212), A070081(212), A070082(212)] = [5,12,13], for s = A070083(212)/2 = (5+12+13)/2 = 15: inradius = sqrt((s-5)*(s-12)*(s-13)/s) = sqrt(10*3*2/15) = sqrt(4) = 2; therefore A070200(212)=2. [Corrected by Rick L. Shepherd, May 15 2008]

Crossrefs

Cf. A070142, A070201, A051516.

Sequence in context: A349879 A226688 A070144 * A070136 A196643 A196598

Adjacent sequences: A070206 A070207 A070208 * A070210 A070211 A070212

Keyword

nonn

Author

Reinhard Zumkeller, May 05 2002

Status

approved