A070205 Number of acute integer triangles with perimeter n having integral inradius.

0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 1, 0, 0, 0, 1, 0, 1, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 2, 0, 0, 0, 0, 0, 1

Offset: 1

Author

Reinhard Zumkeller, May 05 2002

Keywords

• nonn

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

• Eric Weisstein's World of Mathematics, Incircle.
• Eric Weisstein's World of Mathematics, Acute Triangle.
• R. Zumkeller, Integer-sided triangles

Crossrefs

Cf. A024155, A070093, A070140, A070201, A070206.

Formula

a(n) = A070201(n) - A024155(n) - A070206(n).